A shark smaller than a housecat has taken chunks out of nuclear submarines

The cookiecutter shark latches onto prey many times its own size — whales, dolphins, tuna, even other sharks — and twists to gouge out a neat, circular plug of flesh. From the 1970s on, the US Navy found the same round bite marks in the rubber sonar domes of nuclear submarines and had to armor them with fiberglass to stop the damage.

— Standard zoological accounts, Cookiecutter shark