The great scallop is a large bivalve mollusc; its shell familiar to us all with its radiating ridges and characteristic scallop wings by the hinge. The 2 shells are actually different: one is curved like a bowl and the upper shell is flat like a lid. They live in a self-dug hollow on sandy or gravelly seabeds and are filter feeders, filtering out plankton and other micro-organisms. Scallops are a favourite food of starfish, but can actually swim out of harm's way by rapidly opening and shutting their shells, sending out jets of water which propel them over short distances.