Scientists have found fossils that prove unicorns existed, but they were actually pretty terrifying. Millions of children all over the world have grown up with tales of unicorns, with their imaginations fed by the pretty creatures and movies like Legend and the Harry Potter franchise, not to mention my little pony. However, the real animals behind the unicorn myths are more likely to give kids nightmares than sweet dreams. Stories about unicorns were around a long time before Hasbro turned out its first rainbow colored plastic toy. The fantastic creatures are associated with Greek myths, however to the ancient Greeks, they were not considered myths at all, but real live animals from India. These early unicorns were not the graceful creatures we think of today. In fact, Greek historian Sessius gave us the first account in the 5th century BC and describes them as wild asses with long horns. We hear of them again from Pliny the Elder in the 1st century AD, who says they had the head of a stag, the feet of an elephant, and the tail of a boar, while the rest of the body is like that of a horse. The single horned magical beast is not only a European myth, but China and Japan both have their own versions of unicorns, the Killin and Kirin respectively. The Killin was said to appear before the birth or death of someone important. It was particularly horse-like though, with a curled horn and a scally green deer's body and alliance head. Some people believe the Bible contains references to unicorns, although most scholars say this is actually a mistranslation of the Hebrew word Rehem. These creatures are mentioned 9 times in the Bible, where their symbols of strength, but the word most likely refers to an ancient variety of ox. Strength continues to be one of the attributes assigned to unicorns into the Middle Ages, an Alexandrian merchant and traveler from the 6th century, Cosmos and DiCapliostus passed on Ethiopian accounts of the unicorn being a ferocious beast with its power originating in its horn. St. Isador of Seville, who lived in the 7th century, also described the unicorn as a strong animal, able to kill elephants by stabbing them in the stomach. During this time, unicorns weren't all mystical horses yet, sometimes still being described as more like asses or goats. In medieval times, many also thought that unicorn horns were composed of a substance called alicorn. They were believed to have magical properties capable of neutralizing poison and curing mental and physical disease. One group to profit, especially from this belief, were the Vikings, who ran a thriving trade in narwhal horns from the Arctic Ocean, which they sold as unicorn horns. Other real animals that may have inspired the unicorn myth are the orinks, ellen and oryx, and perhaps two horned animals that lost a horn through mutation or a fight. Another possibility is the Indian rhinoceros, and as we'll see, something like a rhinoceros might actually be the origin of the unicorn myth. Even in 1808, a newly discovered species called alasmatherium was named after Gotelfischer von Waldheim, director of the Natural History Museum at Moscow State University. Previously, the alasmatherium had only been identified by fossils and was believed to have been extinct for 350,000 years. Brant suspected the Siberian alasmatherium of being the basis of a totarmeth about a unicorn with a gigantic horn. However, since the alasmatherium was thought to have disappeared about 350,000 years ago, no humans would have been around to see them. Then in March of last year, the skull of an alasmatherium was unearthed and Kazakhstan, putting the date of extinction much later, only 29,000 years ago. Now there was at least a chance that alasmatherium would have been around long enough to be seen by humans and inspire the unicorn legend. Unfortunately, for those who like to think of unicorns as the graceful white haired horses that feature up posters, usually with a rainbow in the background, the alasmatherium was not quite so dainty. Rather than being an ethereal pony, it was closer to being a terrifying monster rhinoceros. The Siberian alasmatherium would have been an intimidating sight, standing around 6 or 7 feet tall and 15 feet long, most likely covered in fur like a mammoth. These mighty animals weighed 4.5 tons. No definite size has yet been given for the horn, but it may have been up to 6 inches long. As its name suggests, the Siberian alasmatherium roamed western Siberia. They were also to be found in southwestern Russia and further south into Eastern Europe. Despite its fearsome appearance, it was a hermivore, like the modern rhinoceros grazing over large areas. Most likely the south of western Siberia was a refugium where this rhino preserved the longest in comparison with the rest of its range, paleontologist Andy Spansky told Fizz.org. There's another possibility that it could migrate and dwell for a while in the more southern areas. Although it's possible that modern humans encountered the alasmatherium, it's not entirely certain that they did. Some like crypticologist Willie Lay, suspect that stories about the species have survived from the prehistoric era, but some accounts like that of 10th century traveler Ibn Fadland seem to describe the giant rhinoceros too accurately to be merely retelling a myth. The unicorns that look a bit more like alasmatherium than the western version are found in stories from those regions where the animal once lived. An old Turkic book contains a description of the Chinese unicorn, Keelan, as a quadrupled with the body of a deer, the tail of a cow, the head of a sheep, the limbs of a horse, the hooves of a cow, and a big horn. So when did unicorns really die out? Nobody knows yet. As new evidence is still being discovered, one theory based on a fossilized Siberian alasmatherium skull is that they died from a meteor impact. Alternatively, they may have been victims of environmental change. Researchers are still working on an answer. 19th century scientists speculated that the alasmatherium must have had a single horn. The whole analogy with the rhinoceros points with the greatest certainty to the previous existence of a horn, wrote Russian zoologist Alexander Brant, which, to judge from the size of the blood vessels, what's encircling the base must have possessed enormous dimensions.