n.
or pileworm
Any of approximately 65 species (family Teredidae) of common marine bivalves that can severely damage wooden structures, including ship hulls and wharves.
Its anterior end is covered by a shell; the rest is a tubelike structure, sometimes up to 6 ft (1.8 m) long. File-like ridges on its white shell cut into wood at 812 rasping motions a minute. It secretes lime to line its burrow, and its tubelike portion extends back to the burrow opening. It ingests food particles and oxygen from the water; some wood is also ingested as food.