Shipworm

Shipworm, much-modified boring clam, also called teredo. It is wormlike in general shape and can attain a length of almost a meter. The shell itself is much reduced, equivalve, and widely gaping, and covers only a part of the animal. The shipworm is a menace to wooden ships and piers, boring into the wood below the waterline.

Scientific classification: Shipworms make up the family Teredinidae of the order Myoida.