The exquisite narwhal (Monodon monoceros), is a medium-sized arctic whale; it’s common name is Old Norse for “Corpse whale,” perhaps named for it’s habit of swimming belly-up for short durations. Charming.
This morbidly named whale’s most notable feature is it’s “horn,” actually a very long tooth seen only on males. In point of fcat narwhals only have two teeth, but to make up for this dearth of dentibus, the left tooth grows in a spiral out of the mouth, reaching lengths as impressive as 7-10 feet. The function of this horn (and why it is only the left tooth) is the source of much speculation; the dominant theory is an old one, first offered by Chuck Darwin himself, who hypothesizes that the horn is a secondary sex characteristic, like a peacock’s feather’s or a human male’s automobile, and is likewise used in mating and male-dominance rituals.
One can only assume that narwhals hear a lot of “are you just happy to see me” jokes.