A unicorn is wonderful white horse. It has a single white horn on its head.

Unicorns have been in stories for thousands of years. Herodotus, the first historian, called the unicorn 'the horned ass of Africa'. The Greek writer Ctesias called it 'the wild ass of India'. It had a white body, a red head and blue eyes. It was as big as a horse and had a long horn on its head.

Pliny described it as a fierce creature. It had the head of a deer, the body of a horse, the feet of an elephant, the tail of a pig and a single long horn.

Could such a creature have existed once? Is it possible for an animal to have just one horn? Yes. A  narwhal has one long horn!