Clipmark

The pholas dactylus or common piddok is a strange little bivalve. The seven inch creature slowly bores into rock, using ridges on the edge of its shell, and then spends the rest of its eight years of life never leaving its hole, except by protruding a double-siphon with which it filters the tides for food particles. There is something else odd about the common piddock. It glows when you eat it.

If the flesh is chewed and held in the mouth, the breath becomes luminous and looks like a real flame" wrote one account of eating the raw shellfish.

Pliny wrote the piddock "glitter both in the mouth of persons masticating them and in their hands, and even on the floor and on their clothes when drops fall on them, making it clear beyond all doubt that their juice possesses a property that we should marvel" wrote Pliny.