Atmospheric Beasts are the strangest of the flying monsters from ufology, cryptozoology and astrobiology. According to eyewitness reports, they are things that seem like living creatures, but they break all the usual rules that we apply to living things. They fly without the need for wings and their bodies are only semi-solid, often partially invisible.
Many atmospheric beast sightings were originally classified as highly unusual UFO reports (in the sense of UFOs being defined as supposed alien spacecraft or machines of some other sort, not in the technical sense of being unidentified flying objects). Noted Bigfoot author Ivan T. Sanderson devoted an entire book to the theory that many UFOs are actually extremely low density animals native to the clouds. One of the most famous atmospheric beasts is the Crawfordsville Monster, sighted in Indiana in 1891, which some researchers classify as a dragon.
For those who believe, atmospheric beasts are very fragile and lightweight creatures who are either native to Earth or are aliens that came from elsewhere. If the latter view is taken, then atmospheric beasts are sometimes thought to have originated in the atmosphere of some other planet, but they can also be thought of as originating in interstellar gas clouds so that they are, in effect, aliens without a native planet, able to "swim" through space. Believers generally consider atmospheric beasts to be non-intelligent, so that even if these creatures did originate somewhere other than earth, they still don't count as sapient extraterrestrials. They're just animals.
In various eyewitness accounts, atmospheric beasts can change their density, becoming smaller, harder masses that are usually metallic in color, or they can become larger and cloudlike, even to the point of invisibility. In some reports, they may glow. Atmospheric beasts may roughly resemble whales and are sometimes called air whales or cloud beasts. Believers think that the atmospheric beasts' normal habitat is high in the air, and they might die if they ever touch the ground. Atmospheric beasts that resemble clouds may engage in behavior that is thought to be impossible for a real cloud, such as squirting a stream of horizontal water at people through "lips" or being far too mobile and animate for witnesses to believe it was just a patch of fog. The more solid kinds of atmospheric beasts may have mouths, eyes, flippers and other features, but these body parts are generally arranged and shaped in a fashion that looks utterly alien, more like an ocean invertebrate's body plan than any animal we are used to seeing on a daily basis.
It is said that when atmospheric beasts die, they fall to earth as a gelatinous mass that may resemble a green, purple, gray or iridescent jelly that evaporates into nothing within minutes, hours, or, at the longest, a few days. This is supposed to explain a type of anomalous event, pwdre ser, that puzzled scientists for some time before they decided that pwdre ser did not exist. Pwdre ser is Welsh for "rot from the stars." This phenomena is also known as gelatinous meteorites or star jelly, and reports of it come from around the world, not just from Wales. Gelatinous meteorites are not always connected with the atmospheric beast theory; they are actually easier to find among collections of Forteana that include reports of many different odd things falling from the sky.
Atmospheric beasts, or things that sound like them, are minor characters in the folklore of many regions. They are often given local names. The English variety is often named "Boneless" or "Shapeless" and resembles a small patch of living, animate fog. Unlike fog, it can be felt as a semi-solid mass. One policeman described an encounter with this creature that had supposedly happened while bicycling. The thing felt like a soft blanket and smelled like mildew. After it rubbed against him, it floated away. It was one of the most terrifying experiences he had ever had. He was convinced that the thing was a living creature. In the Shetland Islands, atmospheric beasts are known as "It" and are thought to be "cloud animals" of some sort. Just as the sea has its own life that is often hidden from view, it is thought that the clouds form a vast atmospheric "sea" far above us, and that "It" is merely an animal that is native to the clouds. Those who report being physically touched by atmospheric beasts often say they felt as if they were being licked by an enormously soft tongue.
In the later decades of the twentieth century, the atmospheric beast theory had been almost forgotten. Serious investigators usually stayed away from it. But, today, interest in atmospheric beasts has been growing, mainly because they now seem more plausible after the recent discovery of what might be a related cryptozoological animal: air rods. People have begun to comb through older reports of miscellaneous random unexplained stuff, a place where a few atmospheric beasts often lurk, and they have also re-examined some of the weirdest UFO reports, which sometimes sound a great deal like the witnesses are actually describing atmospheric beasts.
Since atmospheric beast sightings are rare and the creatures don't have much prominence in folklore either, it has happened that few authors were inspired by the concept and so fiction involving atmospheric beasts is also rare. Two of the most notable films are both Japanese: Dogora is about atmospheric beasts that must consume carbon and threaten civilization, while Space Amoeba is about an atmospheric beast native to Jupiter which hitches a ride to Earth and then converts normal Earth animals into giant monsters. The American movie The Blob is sometimes cited as an atmospheric beast movie, though the connection is iffy. The Blob is supposed to be loosely based on legends of pwdre ser or star jelly, but in the film the presumed atmospheric beast does not die upon contact with the ground but instead travels over land, growing and consuming. The television show Star Trek: The Next Generation occasionally had things like atmospheric beasts that were native to outer space instead of a particular planet's atmosphere, but these creatures were never very prominent.