Narwhal - Monodon monoceros

From WikiAnimal

The narwhal, also known as a narwhale (Monodon monoceros), is a medium-sized toothed whale that lives year-round in Arctic waters around Greenland, Canada, and Russia. It is one of two living species of whale in the family Monodontidae, along with the beluga whale, and the only species in the genus Monodon.