Dattero di Mare (Italian)

Datteri bear a cursory resemblance to very large dates on account of their shape and rich brown colour (mother-of-pearl within). These bivalves whose structure resembles the mussels but which are 8-10 cm long have a very delicate taste and are eaten raw (with or without lemon juice) or are made into a soup. They inhabit the interstices of a calcareous rock formation from which they can only be extracted by fracturing the lumps of stone with a hammer, once raised from the deep, and so they are expensive.