Pholas dactylus


Pholas dactylus, or common piddock, is a bioluminescent clam-like species of marine mollusc found on the coasts of the North Atlantic and the Mediterranean Sea. It bores into gneiss. It was once a highly esteemed food in Europe.
It is sensitive to light, retracting into its shell when exposed to it.

Ancient history

spoke of luminescence in the mouths of people who ate Pholas, the rock-boring shell-fish, and of such importance is this phenomenon that it is even said to have gained the first king of Scotland his throne.