Unicorn

"The blood of a unicorn will keep you alive, even if you are an inch from death, but at a terrible price. You have slain something so pure and defenceless to save yourself, you will have but a half-life, a cursed life, from the moment the blood touches your lips."

- Firenze to Harry Potter

The Unicorn is considered to be a mythological creature that falls under the classification of Magical Beast. They are described as a white, equine creature with a single horn on its forehead.

It is unknown if unicorns truly exist or not, but many believe that they are simply extremely rare and elusive creatures.

Physiology and life cycle
Unicorn foals are said to be born pure gold in color. They remain so until they are about two years old, at which time they turn silver in color. It is believed that their horn grows in at around four-years-old and that they are fully grown at about seven years old, at which they turn a shade of pure white that is so bright that it makes freshly fallen snow look grey in comparison. Their hooves are golden, (remaining so from their gold stage, the first two years of their life), and their blood is silver-blue in color and shines under the moonlight. It is not mentioned in any of the stories how long a Unicorn can live for.

Distribution
Unicorns are said to inhabit the forests of Europe, however they have never been sighted by anyone.

Interaction with humans
Unicorns are said to prefer a woman's touch (particularly those of a virgin woman), but the young ones are more trusting and do not mind men as much. It is said that Unicorns are so fleet-of-hoof that they can rarely be caught by humans.

Magical Properties
It is said that the blood of a unicorn can be drank in order to keep a person alive. However, the act of slaying a unicorn (should one ever be found) will cause the drinker to suffer a cursed life, though the specifics of what this actually entails are not known well. The horn of a unicorn is said to have magical properties that would make it a useful ingredient in potions, such as an antidote to common poisons. In classical myths, unicorn horns have purification properties which are used to dissolve poisons. This could be why it is thought to be used in the antidote to common poisons. It is also said that that hair of a unicorn can be used in various ways. Many believe that unicorn hair can be used in the production of certain objects such as bandages and metal alloys to strengthen them and make them impossible to break. It is also believed that unicorn hair would make a great ingredient in potions.

Unicorns in Folklore
The unicorn was depicted in ancient seals of the Indus Valley Civilization and was mentioned by the ancient Greeks in accounts of natural history by various writers, including Ctesias, Strabo, Pliny the Younger, and Aelian. The Bible also describes an animal, the re'em, which some translations have erroneously rendered with the word unicorn.

In European folklore, the unicorn is often depicted as a white horse-like or goat-like animal with a long horn and cloven hooves (sometimes a goat's beard). In the Middle Ages and Renaissance, it was commonly described as an extremely wild woodland creature, a symbol of purity and grace, which could only be captured by a virgin. In the encyclopedias its horn was said to have the power to render poisoned water potable and to heal sickness. In medieval and Renaissance times, the tusk of the narwhal was sometimes sold as unicorn horn.