Pholas dactylus

Pholas dactylus, or common piddock, is a bioluminescent clam-like species of marine mollusc in the family Pholadidae.

The piddock bores into the substrate for shelter, and lives in a tubular burrow formed by grinding the material away with hard parts of the shell by rotating on the longitudinal axis. It has been known to bore into the hard metamorphic rock gneiss, though it more often lives in softer rock. It is a filter feeder, using its siphons to reach the water outside the burrow. It was once a highly esteemed food in Europe.

It is sensitive to light, retracting into its shell when exposed to it.