It’s likely no surprise that around here, we delight in animals with interesting names—from zedonk to beefalo. One of the few creatures that can top the zedonk for linguistic and zoological oddness is the narwhal.

If you’ve ever seen a creature that looks like a whale with a unicorn horn, you might imagine it’s been Photoshopped. But that’s not fiction—that’s a narwhal.

Where did the narwhal get its name?

This relative of the whale possesses the unique characteristic of a tusk that grows out of its head. The tusk is actually a giant tooth, massive in males and much smaller in females. Its purpose remains somewhat mysterious, but the generally-accepted explanation is that of sexual display, like the feathers of a peacock.

The origin of the name “narwhal” suggests the terror that these rare and unusual creatures must have inspired in ancient sailors. Nar is an Old Norse word for “corpse,” apparently tied to the weird whiteness of the Narwhal’s body. The scientific name bestows a bit more decency: Monodon monoceros, Greek for “one-toothed unicorn.”