In research for a writing assignment, I came across the etymology for narwhal.

Its name is derived from the Old Norse word nár, meaning “corpse”, in reference to the animal’s greyish, mottled pigmentation, like that of a drowned sailor[6] and its summer-time habit of lying still at or near the surface of the sea (called “logging”).[7] The scientific name, Monodon monoceros, is derived from the Greek: “one-tooth one-horn”.[6]