piddock

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A marine bivalve mollusk of the family Pholadidae, having a long shell with which it bores into wood, rock, and clay, often causing destruction of wharf pilings.

Century Dictionary and Cyclopedia

1. n. A mollusk of the genus Pholas or family Pholadidæ; especially, a name of those species which are found in British waters, used rarely for food but much for bait, as P. dactylus; a pholad. It has a long ovate shell with a narrowed tongue-like extension in front, and the entire surface marked with longitudinal and concentric grooves and ridges, and radiating rows of sharp spines. The beaks are anterior and covered with callosities. The piddock is capable of perforating the soft rocks, into which it burrows. It is a common inhabitant of European seas, and in winter is frequently killed by the cold when left exposed by low tide. It is edible, and is sought for by digging it out of the clay or shale. After being removed from the water for a day or so, the animal changes color, and is said to shine like a glow-worm. Also called clam, dactyl, and long oyster. See Pholas, and cut under accessory.

Wiktionary

1. n. Any of the bivalve molluscs of the genus Pholas or family Pholadidae, which burrow into soft rocks.

GNU Webster's 1913

1. n. (Zoöl.) Any species of Pholas; a pholad. See pholas.

WordNet 3.0

1. n. marine bivalve that bores into rock or clay or wood by means of saw-like shells