Shipworms

Shipworms, teredo worms or simply teredo are a group of xylophagic marine bivalve molluscs in the family Teredinidae that consume wood submerged in saltwater. Their elongated, vermiform appearance makes their classification as bivalves not obvious, and sailors generally refer to them as "worms," a term found in the English shipworm and German Schiffsbohrwurm. However, taxonomically shipworms are more akin to clams.

Shipworms are notorious for boring into (and eventually destroying) any wooden structure that is immersed in seawater, including piers, docks, and ships. Shipworms drill passages into wood by using their valves (shells) to rasp away and consume timber. They are sometimes called "termites of the sea".