The narwhal is a toothed whale native to the Arctic.
Narwhals have a distinctive tusk which is usually found only in males. Females rarely grow tusks, but in exceptional cases a female narwhal can develop one. The tusk is not only a distinctive appearance it is also a sensory organ with millions of nerve endings, which allows them to perceive the environment.
In medieval times, narwhals were hunted for their tusks, people would sell them as unicorn horns, earning narwhals the nickname ‘unicorn of the sea’