Unicorn

The unicorn is a legendary creature that has been described since antiquity as a beast with a single large, pointed, spiraling horn projecting from its forehead. It is often used as a symbol of fantasy or rarity.

Dictionary
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 be captured only 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 a unicorn horn.