The first “narluga” skull ever to be discovered. The hybrid mixes traits of its beluga and narwhal parents. (Credit: Mikkel Høegh Post, Natural History Museum of Denmark.)

While visiting West Greenland in the 1980s, an Inuit hunter killed an odd-looking whale. He realized there was something unique about the animal, so he kept its skull. Years later in 1990, a researcher from the Greenland Institute of Natural Resources spotted the specimen mounted on the hunter’s toolshed.

In its top jaw