Retinex Color Theory "Subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple for instance looks green to us at midday, when the main illumination is white sunlight, and also at sunset, when the main illumination is red. This helps us identify objects. The different cone cells of the eye register different ranges of wavelengths of the light reflected by every object in the scene. From this information, the visual system attempts to determine the approximate composition of the illuminating light. One application of theory is that a black and white image superimposed on a monochromatic image could create the illusion of a complete range of colors."

Botflies "The genus Dermatobia contains only one species, D. hominis, the only species of bot fly that attacks humans (in addition to other primates). It is also known as the torsalo. In this species the fly's eggs are vectored by mosquitoes and muscoid flies; the female Dermatobia captures the mosquito and attaches its eggs to the body of it, then releases it. The eggs hatch either while the mosquito is feeding and the larvae may use the mosquito bite area as the entry point, or simply drop off the muscoid fly when it lands on the skin. They develop inside the subcutaneous layers, and after approximately 8 weeks they drop out to pupate for at least a week, typically in the soil. The adults are small gray flies resembling a blowfly."

• Extraction from back of human host
• Look at that giant hole in her head

Candirú "The candirú parasitizes other fish. It swims into the gill cavities of other fish, erects a spine to hold itself in place, and feeds on the blood in the gills, earning it a nickname as the "vampire fish of Brazil". It is feared by the natives because it is attracted to urine, and if the bather is nude it will swim into an orifice (the vagina and even the penis—and deep into the urethra) and because of spines protruding from the fish, it is almost impossible to remove except through surgery. The fish locates its host by following a water flow to its source and thus urinating while bathing increases the chance of a candirú homing in on a human urethra. Natives have also been known to bathe facing the current, as doing so would decrease the chances of the organism lodging itself in the rectum.[citation needed] Other orifices such as the penis or vagina are covered up with the use of hands."

• Yep I also heard about this from Grey's Anatomy
• Perverted fish

Parasitic Twin "A parasitic twin is the result of a situation related to the process that results in vanishing twin and conjoined twins; a twin embryo begins developing in utero, but does not fully separate and one maintains dominate development at the expense of the other. Parasitic twins are also known as asymmetrical conjoined twins or unequal conjoined twins. Parasitic twins are a variation of conjoined twins—except one of the twins stopped developing during gestation and is now vestigial to a healthy, otherwise mostly fully-formed individual twin. The undeveloped twin is defined as parasitic, rather than conjoined, because it is incompletely formed or wholly dependent on the body functions of the complete fetus."

• Video of man with parasitic twin

Bombay Blood "People who have Bombay blood phenotype do not express H antigens in their blood cells, which means they can donate to any member of the ABO blood group system, but can only be transfused with blood from other Bombay phenotype individuals. Given that this condition is very rare, any person with this blood group who needs an urgent blood transfusion will probably be unable to get it, as no blood bank would have any in stock. Those anticipating the need for blood transfusion may bank blood for their own use, but this option is not available in cases of accidental injury."

Prions "Short for proteinaceous infectious particle, an infectious agent which according to the 'protein only' hypothesis is composed only of protein. Prions cause a number of diseases in a variety of mammals, including bovine spongiform encephalopathy in cattle and Creutzfeldt-Jakob disease in humans. All known prion diseases affect the structure of the brain or other neural tissue, and all are currently untreatable and fatal."

Cri du chat "French for 'cry of the cat', this rare genetic disease is the result of deletion of a portion of chromosome 5. Problems in laryngeal development results in sounds similar to that of a meowing kitten. It is also associated with several neurological impairment and mental retardation. Those afflicted often do not survive past infancy."

Coloboma "Coloboma of the iris is a congenital defect of the iris of the eye. It is visible as a hole, split, or cleft in the iris. It is caused by failure of the choroid fissure to fuse completely in fetal development. Although not considered a serious medical condition, coloboma may allow a secondary image to focus on the back of the eye, causing a ghost image, blurred vision, or decreased visual acuity."

Angelman Syndrome "Characterized by intellectual and developmental delay, speech impediment, sleep disturbance, unstable jerky gait, seizures, hand flapping movements, frequent laughter/smiling and usually a happy demeanour. Those inflicted were originally described as 'puppet children', but this description is now considered pejorative. This condition is a classic example of genetic imprinting caused by deletion or inactivation of critical genes on the maternally inherited chromosome 15. Because Angelman Syndrome is not an illness, but a genetic condition, there is no currently available cure."

Prader-Willi syndrome "Prader-Willi syndrome has no cure. However, several treatments are in place to lessen the condition's symptoms. Growth hormone replacement therapy improves body composition and increases linear height. During infancy, subjects should undergo therapies to improve muscle tone. Speech and occupational therapy are also indicated. During the school years, children benefit from a highly structured learning environment as well as extra help. Throughout their lives, the subject's food should literally be kept under lock and key, since the largest problem associated with the syndrome is severe obesity. This condition is due to deletion or inactivation of genetically imprinted genes on the paternally inherited chromosome 15. The sister syndrome is Angelman Syndrome."

Dermatopathia pigmentosa reticularis "A form of a rare sex-linked ectodermal dysplasia congenital disorder that afflicts females. Symptoms include lack of sweat glands, thin hair, brittle nails, mottled skin, and lack of fingerprints."

Scotopic sensitivity syndrome "A broadly defined visual perceptual disorder affecting primarily reading and writing based activities, particularly visual distortions some individuals reported when reading from white paper. The use of colored plastic overlays for such individuals greatly improved the reading abilities."

Synesthesia "Though often stereotyped in the popular media as a medical condition or neurological aberration, synesthetes themselves do not experience their synesthetic perceptions as a handicap. To the contrary, most report it as a gift—an additional "hidden" sense—something they would not want to miss. Most synesthetes have become aware of their "hidden" and different way of perceiving in their childhood. Some have learned how to apply this gift in daily life and work. Synesthetes have used their gift in memorizing names and telephone numbers, mental arithmetic, but also in more complex creative activities like producing visual art, music, and theater."

Umami "One of the five basic tastes sensed by specialized receptor cells present on the human tongue. Umami is a Japanese word meaning 'savory' and thus applies to the sensation of savoriness—specifically, to the detection of glutamates, which are especially common in meats, cheese and other protein-heavy foods. The action of umami receptors explains why foods treated with monosodium glutamate often taste fuller. Umami was first identified in 1908 by Kikunae Ikeda of the Tokyo Imperial University while researching the strong flavor in seaweed broth. Ikeda isolated monosodium glutamate as the chemical responsible and, with the help of the Ajinomoto company, began commercial distribution of these products."

Cysts "Closed sacks having a distinct membrane and develosion on the nearby tissue. They may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, the cyst will remain in the tissue permanently and can be removed by surgery and by taking medication that will dissolve the sack."

• Why you should listen to your doctor
• Oozing like a fountain

Sonic hedgehog gene "This gene plays a key role in regulating vertebrate organogenesis, such as in the growth of digits on limbs and organization of the brain. Some clinicians and scientists criticize giving genes frivolous or quirky names, calling it inappropriate that patients with a serious illness or disability are told that they or their child have a mutation in a gene such as Sonic hedgehog."

Pokemon gene "Zbtb7, originally named Pokemon, is a gene that may act as a master switch for cancer, and is responsible for the evolution of cancer. The gene is unique in that it is needed for other oncogenes to cause cancer. Discovery of the gene was first published in the January 2005 issue of Nature. The original name stands for 'POK erythroid myeloid ontogenic factor' and is most likely a backronym of the Pokemon media franchise. Nintendo subsidiary Pokemon USA, not wanting the bad press inherent with its trademark sharing a name with a cancer-causing gene, threatened the center with legal action resulting in the renaming of the gene to Zbtb7."

Blood substitutes "When blood is lost, the greatest immediate need is to stop blood loss. The second greatest need is replacing the lost volume. This way remaining red blood cells can still oxygenate body tissue. Normal human blood has a significant excess oxygen transport capability, only used in cases of great physical exertion. Provided blood volume is maintained by volume expanders, a quiescent patient can safely tolerate very low hemoglobin levels, less than 1/3rd of a healthy person. However in extreme cases of oxygen deficit, artificial blood can fulfill the oxygen therapeutic function. Perfluorocarbons (PFCs), in particular, may be useful in cases of myocardial infarction or stroke because these small oxygen carrying molecules are able to pass clots that would normally block blood cells."

Liquid breathing "A form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid rather than breathing air. It is used for medical treatment such as infants with acute Respiratory distress syndrome, and could some day find use in deep diving and space travel. Liquid breathing is sometimes called fluid breathing, but this can be confusing because both liquids and gases can be called fluids."

Pulse oximeter "A medical device that indirectly measures the oxygen saturation of a patient's blood and changes in blood volume in the skin, producing a photoplethysmograph. It is often attached to a medical monitor so staff can see a patient's oxygenation at all times."

Karōshi "Can be translated quite literally from Japanese as 'death from overwork', is occupational sudden death. The major medical causes of karōshi deaths are heart attack and stroke due to stress. Usually, Japan's rise from the devastation of World War II to economic prominence in the post-war decades has been regarded as the trigger for what has been called a new epidemic. It was recognized that employees cannot work for twelve or more hours a day, six or seven days a week, year after year, without suffering physically as well as mentally. A recent measurement found that a Japanese worker has approximately two hours overtime a day on average. In almost all cases, the overtime is unpaid. The recent international expansion of Japanese multinationals has also led to an export of the Karōshi culture to countries such as China, Korea and Taiwan."

Norman Bethune "Dr. Henry Norman Bethune was a Canadian physician, medical innovator, and humanitarian. He died on November 12, 1939, of blood poisoning from a cut he received when performing surgery, while with the Communist Party of China's Eighth Route Army in the midst of the second Sino-Japanese War. Virtually unknown in his homeland during his lifetime, Doctor Bethune finally received international recognition when Chairman Mao Zedong of the People's Republic of China published his essay entitled In Memory of Norman Bethune (in Chinese: 紀念白求恩), which documented the final months of the doctor's life in China. Mao made the essay required reading for the entire Chinese population. Mao concluded in that essay: We must all learn the spirit of absolute selflessness from him. With this spirit everyone can be very helpful to each other. A man's ability may be great or small, but if he has this spirit, he is already noble-minded and pure, a man of moral integrity and above vulgar interests, a man who is of value to the people."

Uncanny Valley "As a robot is made more humanlike in its appearance and motion, the emotional response from a human being to the robot will become increasingly positive and empathic, until a point is reached beyond which the response quickly becomes that of strong repulsion. However, as the appearance and motion continue to become less distinguishable from a human being's, the emotional response becomes positive once more and approaches human-human empathy levels. This area of repulsive response aroused by a robot with appearance and motion between a "barely-human" and "fully human" entity is called the Uncanny Valley. The name captures the idea that a robot which is "almost human" will seem overly "strange" to a human being and thus will fail to evoke the empathetic response required for productive human-robot interaction."

Neodymium magnet "A powerful magnet made of a combination of neodymium, iron, and boron (Nd₂Fe₁₄B). Used for stabilization and angular head motors in computer hard drives, neodymium magnets are also popular with hobbyists, and a small magnet can have amazing properties. Neodymium magnets should always be handled carefully. Some that are slightly larger than the size of a penny are powerful enough to lift over 10 kilograms. They are hazardous; able to interfere with pacemakers and implanted heart devices with deadly consequences. Larger neodymium magnets can severely pinch skin or fingers, or even break bones when suddenly attracted to a magnetic object. Operating a large neodymium magnet close to smaller magnetic objects (keys, pens, etc.) and larger magnetic surfaces (radiator or a car, for example) can be dangerous if the person is caught between the magnet and the magnetic object or surface.If swallowed, neodymium magnets can cause lethal conditions by joining up inside the intestine."

Aerogel "A low-density solid-state material derived from gel in which the liquid component of the gel has been replaced with gas. The result is an extremely low density solid with several remarkable properties, most notably its effectiveness as an insulator. Despite what their name may suggest, aerogels are dry materials and do not resemble a gel in their physical properties (the name comes from the fact that they are derived from gels). Pressing softly on an aerogel typically does not leave a mark; pressing more firmly will leave a permanent dimple. Pressing firmly enough will cause a catastrophic breakdown in the sparse structure, causing it to shatter like glass--a property known as friability. Despite the fact that it is prone to shattering, it is very strong structurally. Its impressive load bearing abilities are due to the dendritic microstructure, in which spherical particles of average size 2-5 nm are fused together into clusters. Silica aerogel is the most common type of aerogel and the most extensively studied and used. It is a silica-based substance, derived from silica gel. The world's lowest-density solid is a silica aerogel (the latest and lightest versions of this substance have a density 1 mg/cm³, 1/1000 as dense as water), produced by the Lawrence Livermore National Laboratory."

Three-dimensional printing "One variation consists of an inkjet printing system. Layers of a fine powder (plaster and resins) are selectively bonded by "printing" a water-based adhesive from the inkjet print head in the shape of each cross-section as determined by a CAD (computer aided design) file. This technology is the only one that allows for the printing of full color prototypes. 3D printing technology is currently being studied by biotechnology firms and academia for possible use in tissue engineering applications where organs and body parts are built using inkjet techniques. Layers of living cells are deposited onto a gel medium and slowly built up to form three dimensional structures. Several terms have been used to refer to this field of research: Organ printing, bio-printing, and computer-aided tissue engineering among others."

Von Neumann machines "A self-replicating machine would need to have the capacity to gather energy and raw materials, process the raw materials into finished components, and then assemble them into a copy of itself. It is unlikely that this would all be contained within a single monolithic structure, but would rather be a group of cooperating machines or an automated factory that is capable of manufacturing all of the machines that make it up. The factory could produce mining robots to collect raw materials, construction robots to put new machines together, and repair robots to maintain itself against wear and tear, all without human intervention or direction. The advantage of such a system lies in its ability to expand its own capacity rapidly and without additional human effort; in essence, the initial investment required to construct the first self-replicating device would have an infinitely large payoff with no additional labor cost. Such a machine violates no physical laws, and we already possess the basic technologies necessary for some of the more detailed proposals and designs."

Ekranoplan "During the Cold War, ekranoplans were sighted for years on the Caspian Sea as huge, fast-moving objects. The name Caspian Sea Monster was given by US intelligence operatives who had spotted the huge vehicle, which looked like an airplane with the outer halves of the wings removed. After the end of the Cold War, the "monster" was revealed to be one of several Soviet military designs meant to fly only a few meters above water, saving energy and staying below enemy radar."

Mass driver "A method of spacecraft propulsion that would use a linear motor to accelerate payloads up to high speeds. All existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets."

Repeating crossbow "A crossbow where the separate actions of stringing the bow, placing the bolt and firing it can be accomplished with a simple one-handed movement, all the while keeping the crossbow stationary. This allows the bow to fire at a faster rate compared to a normal crossbow. A magazine containing a number of bolts is present on top of the bow and the mechanism is worked by moving a rectangular lever forward and backward."

Meissner effect "The Meissner effect effectively tells us that in a weak applied field, a superconductor expels all magnetic flux. The phenomenon was discovered by Walther Meissner and Robert Ochsenfeld in 1933 by measuring the flux distribution outside of tin and lead specimens as they were cooled below their transition temperature in the presence of a magnetic field. They found that below the superconducting transition temperature that the specimens became perfectly diamagnetic, cancelling all flux inside. The experiment demonstrated for the first time that superconductors were more than just perfect conductors and provided a uniquely defining property of the superconducting state."

Helium-3 refrigerator "A simple device for obtaining temperatures down to about 0.2 kelvins. A 1-K pot is used to liquefy a small amount of helium-3 in a small vessel called a helium-3 pot. Evaporative cooling of the liquid helium-3 cools the helium-3 pot to a fraction of a degree kelvin."

Sonoluminescence "Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound. The mechanism of the phenomenon remains unsettled. Some of the theories include hotspot, bremsstrahlung radiation, collision induced radiation and corona discharges, non-classical light, proton tunneling, electrodynamic jets, and fractoluminescent jets. An unusually exotic theory of sonoluminescence, which has received much popular attention, yet is considered to have a marginal effect on the mechanism of SBSL by the scientific community at large, is the Casimir energy theory proposed by Claudia Eberlein, a physicist at the University of Sussex. In 1996, it was suggested that the light in sonoluminescence is generated by the vacuum around the bubble in a process similar to Hawking radiation, the radiation generated by the edges of black holes. Quantum theory holds that a vacuum is filled with virtual particles, and the rapidly moving interface between water and air converts virtual photons into real photons. This is related to the Unruh effect or the Casimir effect. If true, sonoluminescence may be the first observable example of quantum vacuum radiation."

One-electron universe "Commonly associated with Richard Feynman when he mentioned it in his Nobel lecture, postulates that there exists only a single electron in the universe, propagating through space and time in such a way as to appear in many places simultaneously. The hypothesis immediately confronts two apparent hurdles. The first is the annihilation reaction of an electron and a positron; the second the imbalance of matter and antimatter in the universe. While the first is neatly overcome by the realisation that this event is the precise moment in which the particle reverses its trajectory in time, the second is irreconcilable with our current understanding that matter strongly outweighs antimatter."

Synthetic diamond "Despite being occasionally characterized as 'fake', synthetic diamond is molecularly identical to the carbon allotrope defined as diamond when referring to naturally occurring diamond. As such, it shares nearly identical material properties. Depending on how the synthetic diamond is made it can have some superior properties, such as greater purity and hardness."

Defence Scheme No. 1 "Defence Scheme No. 1 was created in 1921 and details a surprise attack on the northern U.S. as soon as possible after evidence was received of an American invasion of Canada. According to the plan, Canadian troops would immediately be sent to seize Seattle, Washington; Great Falls, Montana; Minneapolis, Minnesota; and Albany, New York in a surprise attack. In case of heavy resistance, the Canadians would retreat to their own borders, destroying bridges and railways to hinder any retaliation by the Americans. The purpose of the invasion would be to allow time for Canada to prepare its war effort and to receive aid from Britain, or to limit the American invasion before the US government opted to discontinue the incursions. Defence Scheme No. 1 serves as a counterpart to the Americans' War Plan Red, a plan to invade Canada, drafted in 1930."

Air Transat Flight 236 "On August 24, 2001, Flight 236 ran out of fuel over the Atlantic Ocean. the pilots had noticed a fuel imbalance between the fuel tanks in the left and right wings of the aircraft and had attempted to remedy this by opening a cross-feed valve between the tanks. This only caused fuel from the operational tank to be wasted through the leak in the engine on the other side. Without fuel, an aircraft's engines cannot provide thrust or electrical power. Control of the aircraft depended on the last backup, a ram air turbine, which supplied limited power to hydraulic and electrical systems. The pilots of the Airbus A330 were eventually able to glide the aircraft to a landing at Lajes Air Base, Terceira Island in the Azores. The reported landing speed was about 200 knots indicated airspeed, higher than the normal speed of 130 to 145KIAS. There were no fatalities, but there were minor injuries. The favorable outcome was also due to the flight being rerouted on a more southerly route across the Atlantic due to congestion, bringing them closer to the Azores. "

Tenerife Air Disaster "The single largest air disaster in aviation history occurred on March 27, 1977 when two Boeing 747 airliners collided on the island of Tenerife, Canary Islands, Spain. KLM Royal Dutch Airlines Flight 4805 was taking off on the only runway of the airport when it crashed into Pan American World Airways Flight 1736 which was taxiing on the same runway. All 234 passengers and 14 crew members in the KLM plane were killed, and 326 passengers and 9 crew members aboard the Pan Am flight perished, primarily due to the fire and explosions resulting from the fuel spilled in the impact. Fifty-six passengers and 5 crew members aboard the Pan Am survived."

• National Geographic Channel documentary on the disaster

Ethiopian Airlines Flight 961 "The pilot tried to make an emergency landing on the airport at Prince Said Ibrahim International Airport, Grand Comoro, but a fight with the hijackers at the last minute caused him to lose his visual point of reference, leaving him unable to locate the airport. While still fighting with the hijackers, he then tried to ditch the aircraft in shallow waters 500 metres off Le Galawa Beach Hotel near Mitsamiouli at the northern end of Grand Comoro island. The left engine and wingtip struck the water first, causing the aircraft to break up. Of the 175 passengers and crew members, 123 were killed including the three hijackers."

Battle of Leyte Gulf "Generally considered to be the largest naval battle of World War II and also, by some criteria, the largest naval battle in history. The United States 3rd and 7th Fleets, including some Australian warships, comprised 8 large aircraft carriers, 24 light/escort carriers, 12 battleships, 24 cruisers, 141 destroyers, many other ships, and around 1,500 aircraft. They won a decisive victory over Japanese forces, which consisted of four aircraft carriers, nine battleships, 19 cruisers, 34 destroyers and several hundred aircraft. The opposing fleets carried a total of about 200,000 men."

Liquid crystal "Substances that exhibit a phase of matter that has properties between those of a conventional liquid, and those of a solid crystal. There are many different types of Liquid Crystal phases, which can be distinguished based on their different optical properties such as birefringence. When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have a distinct texture. Applications in technology include ubiquitous liquid crystal displays, smart glass, and thermometers."

High Frequency Active Auroral Research Program "An investigation project to understand, simulate and control ionospheric processes that might alter the performance of communication and surveillance systems. Started in 1993, the project is proposed to last for a period of twenty years. The project is jointly funded by the United States Air Force, the Navy, and the University of Alaska."

Project Babylon "A project allegedly commissioned by the Iraqi president Saddam Hussein during the Iran-Iraq War to build a series of superguns. The design was based on research from the 60s Project HARP led by the Canadian artillery expert Gerald Bull."

Project Mohole "An ambitious attempt to drill through the Earth's crust into the Mohorovičić discontinuity, and to provide an Earth science complement to the high profile Space Race. It was led by the American Miscellaneous Society with funding from the National Science Foundation. Phase One was executed in spring 1961. Off the coast of Guadalupe, Mexico, five holes were drilled, the deepest at 183 m (601 ft) below the sea floor in 3,500 m (11,700 ft) of water. Phase One proved that both the technology and expertise were available to drill into the Earth's mantle. However, Phase Two was dissolved in 1966 due to poor management and cost overruns."

Buran Space Shuttle "The Soviet reusable spacecraft program Buran began in 1976 at TsAGI as a response to the United States Space Shuttle program. The project was the largest and the most expensive in the history of Soviet space exploration. After the first flight, the project was suspended due to lack of funds and the political situation in the Soviet Union. The two subsequent orbiters, which were due in 1990 and 1992 were never completed. The project was officially terminated on June 30, 1993 by President Boris Yeltsin. At the time of its cancellation, 20 billion rubles had been spent on the Buran program."

Richard Feynman "An American physicist known for expanding the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, and particle theory. For his work on quantum electrodynamics, Feynman was a joint recipient of the Nobel Prize in Physics in 1965. Feynman was a keen popularizer of physics in both his books and lectures, notably a 1959 talk on top-down nanotechnology called There's Plenty of Room at the Bottom, and The Feynman Lectures on Physics. Feynman is also known for his semi-autobiographical books Surely You're Joking, Mr. Feynman! and What Do You Care What Other People Think?, and through books about him, such as Tuva or Bust!. He was also known as a prankster, juggler, a proud amateur painter, and a bongo player. Richard Feynman was regarded as an eccentric and a free spirit. He liked to pursue multiple seemingly independent paths, such as biology, art, percussion, Maya hieroglyphs, and lock picking."

Ebu Gogo "A human-like creature (or race of creatures) which appears in the mythology of the people of the island of Flores, Indonesia, of similar form to the leprechaun or elf. These "little people" are said to be about one meter tall, covered in hair, pot-bellied and with ears that stick out. They are held to walk somewhat awkwardly and are often said to be 'murmuring' in what is assumed to be their own language. It is also said by the islanders that the Ebu Gogo can repeat what is said to them in parrot-like fashion. The discovery in 2003 on Flores of remains of a meter-tall hominid, Homo floresiensis, suggests a more literal interpretation of the Ebu Gogo stories. H. floresiensis survived at least until 12,000 years ago and probably survived longer."

Mantis shrimp "Aggressive and typically solitary sea creatures that spend most of their time hiding in rock formations or burrowing intricate passageways in the sea-bed. They either wait for prey to chance upon them or, unlike most crustaceans, actually hunt, chase and kill living prey. Mantis shrimp are the only known animals with hyperspectral colour vision. Their eyes are mounted on mobile stalks and move about independently of each other, and are considered to be the most complex eyes in the animal kingdom. Mantis shrimp appear to be highly intelligent, are long lived and exhibit complex behaviour such as ritualised fighting. Scientists have discovered that some species use fluorescent patterns on their bodies for signaling with their own and maybe even other species, expanding their range of behavioural signals. They can learn and remember well, and are able to recognise individual neighbours with whom they frequently interact. They can recognise them by visual signs and even by individual smell. Many have developed a complex social behaviour to defend their space from rivals. They strike by rapidly unfolding and swinging their raptorial claws at the prey, and are capable of inflicting serious damage on victims significantly greater in size than themselves. They can deploy at an acceleration of 10,400 g and speeds of 23 m/s from a standing start, enough to generate cavitation bubbles. The collapse of these bubbles produce measurable forces on their prey in addition to the instantaneous forces of 1,500 N that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follows. Even if the initial strike misses the prey, the resulting shock wave can be enough to kill or stun the prey. In kept in captivity, they have been known to crack aquarium tanks.

Kudzu "Kudzu is sometimes referred to as 'the plant that ate the South', a reference to how kudzu's explosive growth has been most prolific in the southeastern United States due to nearly ideal growing conditions. Significant sums of money and effort are spent each growing season to prevent kudzu from taking over roads, bridges, power lines, and local vegetation. Kudzu vines can make walking across an area nearly impossible, as it takes over all horizontal and vertical surfaces, both natural and artificial. Its dense growth obstructs all views and movement into the area. It kills or degrades other plants by smothering them under a solid blanket of leaves, by girdling woody stems and tree trunks, and by breaking branches or uprooting entire trees and shrubs through its weight."

Upas tree "The tree was said to destroy all animal life within a radius of 15 miles or more. The poison was fetched by condemned malefactors as an alternative to immediate execution; the criminal had to wait till the wind was blowing from him toward the tree, get the poison and get back before the wind changed; scarcely two out of twenty returned."

Giant isopod "They are thought to be abundant in cold, deep waters of the Atlantic and Pacific Ocean. Bathynomus giganteus, the species upon which the generitype is based, is the largest known isopod and is the one most often referred to by the common name "giant isopod". Maturing to a length between 19 and 37 cm, and maximally reaching a weight of approximately 1.7 kg, giant isopods are a good example of deep-sea gigantism; most other isopods range in size from 1–5 cm. Their morphology is nonetheless familiar to most people as giant isopods closely resemble their terrestrial cousins, the woodlice: their bodies are dorso-ventrally compressed, protected by a rigid, calcareous exoskeleton composed of imbricate segments."

Ryugyong Hotel "A towering, empty concrete shell that was once intended for use as a hotel in Sojang-dong, in the Potong-gang District of Pyongyang, North Korea. The hotel's name comes from one of the historic names for Pyongyang: Ryugyong, or 'capital of willows.' Its 105 stories rise to a height of 330 m, and it boasts some 360,000 m² of floor space, making it the most prominent feature of the city’s skyline and by far the largest structure in the country. North Korean leadership envisioned the project as a channel for Western investors to step into the marketplace. A firm, the Ryugyong Hotel Investment and Management Co., was established to attract foreign investment. A representative for the North Korean government promised relaxed oversight, saying, 'The foreign investors can even operate casinos, nightclubs or Japanese lounges if they want to.' Construction started in 1987 and ceased in 1992. The basic structure is complete, but no windows, fixtures, or fittings have been installed, and it has never been certified safe for occupancy. The concrete used to build the hotel was very poor, making the structure unsafe, and it has worn down even more over the years. The North Korean government is trying to invite foreign investment of $300 million to improve and finish the hotel. In the meantime, it has removed the Ryugyong from maps and stamps."

• Satellite view
• A unique architectural design in complete discord from the surroundings

Millau Viaduct "A large cable-stayed road-bridge that spans the valley of the River Tarn near Millau in southern France. It is the tallest vehicular bridge in the world, with one mast's summit at 343 metres — slightly taller than the Eiffel Tower and only 38 m shorter than the Empire State Building."

Burj Dubai "A supertall skyscraper currently under construction in the 'New Downtown' of Dubai, United Arab Emirates. As of 21 July 2007, the tower's developers reported the Burj Dubai's height as 512.1 meters with 141 completed floors, surpassing Taipei 101 as the tallest high-rise building in the world."

Mont Saint-Michel "Before the construction of the first monastic establishment in the 8th century, the island was called Mont Tombe. According to legend, the archangel Michael appeared to St. Aubert, bishop of Avranches, in 708 and instructed him to build a church on the rocky islet. Aubert repeatedly ignored the angel's instruction, until Michael burned a hole in the bishop's skull with his finger. The Mont Saint-Michel and its bay were added to the UNESCO list of World Heritage Sites in 1979, as they rank very high on such World Heritage Site criteria as cultural, historical, and architectural significance, as well as human-created and natural beauty."

Spite house "A spite house is a building, generally in an urban environment, constructed because someone the builder feels has wronged him does not want it there. Usually they serve primarily as obstructions, blocking out light or access to neighboring buildings, or as flamboyant symbols of defiance. Because actually inhabiting such structures is usually a secondary goal at most, they often have strange and impractical layouts."

Vajont Dam "Completed in 1961 under Monte Toc 100 km north of Venice, Italy, it was one of the highest dams in the world measuring 262 meters high, 27 meters thick at the base and 3.4 meters at the top. On October 9, 1963 at approximately 10:35pm, the combination of the third drawing-down of the reservoir and heavy rains triggered an enormous landslide of about 260 million cubic meters of forest, earth, and rock, which fell into the reservoir at up to 110 km per hour (68 mph). The resulting displacement of water caused 50 million cubic meters of water to over top the dam in a 250-meter high wave. Despite this, the dam's structure was largely undamaged — the top meter or so of masonry was washed away, but the basic structure remained intact. However, the flooding caused by the landslide destroyed the villages of Longarone, Pirago, Rivalta, Villanova and Faè, killing 1,450 people. Many small villages in the territory of Erto e Casso and the village of Codissago, near Castellavazzo, were largely wrecked. Almost 2,000 people perished. Damage was also caused by the air displacement caused from the immense 'splash' in surrounding villages."

• Details about the Vajont landslide
• More details about the Vajont landslide
• Did the landslide occur naturally or was it man-made?

Principality of Sealand "During World War II, HM Fort Roughs was constructed by the UK as one of the Maunsell Forts, primarily for defence against German mine-laying aircraft that might be targeting the estuaries that were part of vital shipping lanes. It comprised a floating pontoon base with a superstructure of two hollow towers joined by a deck upon which other structures could be added. On September 2, 1967, the fort was occupied by Major Paddy Roy Bates, a British subject and pirate radio broadcaster."

Rat king "Rat kings are cryptozoological phenomena said to arise when a number of rats become intertwined at their tails, which become stuck together with blood, dirt, and excrement. The animals consequently grow together while joined at the tails, which are often broken. The phenomenon is particularly associated with Germany, where the majority of instances have been reported. Most researchers presume the creatures are legendary and that all supposed physical evidence is hoaxed, such as mummified groups of dead rats with their tails tied together. Reports of living specimens remain unsubstantiated. One theoretical cause for the phenomenon is cramped living space; young rats might live too closely together, becoming inextricably entangled. However, the normal behavior of rats, which generally seek their own comfort, speaks against this theory. No scientific study has been performed to prove a natural cause of the phenomenon."

Bhopal disaster "On the morning of December 2, 1984, a holding tank with 43 tonnes of stored MIC from the Union Carbide factory, overheated and released toxic methyl isocyanate gas mixture, which, being heavier than air, rolled along the ground through the surrounding streets. The transportation system in the city collapsed and many people were trampled trying to escape. According to the Bhopal Medical Appeal, around 500,000 people were exposed. Approximately 20,000 are believed to have died as a result. Over 120,000 continue to suffer the effects of the disaster, such as breathing difficulties, cancer, serious birth-defects, blindness, gynecological complications and other related problems. Union Carbide denies allegations of wrongdoing, claiming that the appropriate safety systems were in place and operative."

Snowball Earth "The hypothesis proposes that the Earth was entirely covered by ice in part of the Cryogenian period of the Proterozoic eon, and perhaps also at other times in Earth history. The hypothesis was developed to explain sedimentary glacial deposits at tropical latitudes during the Cryogenian period (850 to 630 million years ago) and other enigmatic features of the Cryogenian geological record. After the last big freeze ended, multicellular evolution began to accelerate. Snowball Earth remains controversial, and is contested by various scientists who dispute both the geophysical feasibility of a completely frozen ocean, or the geological evidence upon which the hypothesis is based."

Clearwater Lakes "Lac à l'Eau Claire are a pair of circular lakes on the Canadian Shield in Quebec near Hudson Bay.The lakes fill circular depressions that are interpreted as paired impact craters. The eastern and western craters are 26 km and 36 km in diameter, each crater has the same age, 290 ± 20 million years are believed to have formed simultaneously. The impactors may have been gravitationally bound as a binary asteroid. This suggestion was first made by Thomas William Hamilton in a letter to Sky & Telescope magazine in support the then-controversial theory that asteroids may possess moons."

Richat Structure "A prominent circular feature in the Sahara desert of Mauritania, has attracted attention since the earliest space missions because it forms a conspicuous bull's-eye in the otherwise rather featureless expanse of the desert. The structure, which has a diameter of almost 50 kilometres has become a landmark for space shuttle crews. Initially interpreted as a meteorite impact structure because of its high degree of circularity, it is now thought to be a symmetrical uplift that has been laid bare by erosion. Paleozoic quartzites form the resistant beds outlining the structure."

Great Blue Hole "A large underwater sinkhole off of the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 60 miles from the mainland and Belize City. It was formed as a limestone cave system during the last ice age when sea levels were much lower. As the ocean began to rise again the caves flooded, and the roof collapsed."

Ferdinandea "A submerged volcanic island that forms part of the newly discovered underwater volcano Empedocles 30 km south of Sicily. Currently a seamount, eruptions have raised it above sea level several times before erosion has caused it to submerge again. When it last rose above sea level after erupting in 1831, a four-way dispute over its sovereignty began, which was still unresolved when it disappeared beneath the waves again in early 1832."

Exoplanet "An exoplanet is a planet beyond the Solar System. As of May 2007, the count of known exoplanets stands at 241. The vast majority have been detected through various indirect methods rather than actual imaging. Most of them are giant planets likely to resemble Jupiter more than Earth. Most known exoplanets orbit stars roughly similar to our own Sun, that is, main-sequence stars of spectral categories F, G, or K. One reason is simply that planet search programs have tended to concentrate on such stars. But even after taking this into account, statistical analysis suggests that lower-mass stars (red dwarfs, of spectral category M) are either less likely to have planets or have planets that are themselves of lower mass and hence harder to detect. Recent observations by the Spitzer Space Telescope indicate that stars of spectral category O, which are much hotter than our Sun, produce a photo-evaporation effect that inhibits planetary formation. A subset of exoplanets are interstellar planetary masses, objects which have equivalent mass to planets and are not gravitationally bound to any star, and move through space as independent objects. Several astronomers claim to have detected such objects, but those detections remain unconfirmed. Some astronomers refer to these objects as 'planets', usually because they believe such objects were planets that were ejected from orbiting a star. However, others believe that the definition of 'planet' should depend on current observable state, and not origin. Additionally, these objects may form on their own through gas cloud collapse like stars; in which case they would never have been planets."

Lagrangian point "Five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to rotate with them. They are analogous to geosynchronous orbits in that they allow an object to be in a "fixed" position in space rather than an orbit in which its relative position changes continuously."

Fermi Paradox "The apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for, or contact with, such civilizations. The extreme age of the universe and its vast number of stars suggest that if the Earth is typical, extraterrestrial life should be common. Fermi questioned why, if a multitude of advanced extraterrestrial civilizations exist in the Milky Way galaxy, evidence such as spacecraft or probes are not seen."