The skin of a nuclear submarine was pitted with craters the size of Vanilla Wafers. It was the work of...
Isistius brasiliensis:
A shark species the size and shape of a police officer's billy club. It cuts round plugs into the skin of whales, sea lions, porpoises, tunas, and billfishes. Then it rotates its body as its suction-cup mouth sucks out the flesh. The shark also liked the looks of the nuclear submarine--and tried it out.
The cookie cutter is one of the most luminous sharks. Hundreds of light-producing organs on its underside and head make the shark glow an eerie green in deep, dark water.
Information from 365 Surprising Scientific Facts, Breakthroughs, and Discoveries by Sharon Bertsch McGrayne.