This enormous shellfish, an inhabitant of tropical seas, is the world’s largest bivalve mollusc alive today and the heaviest of all living bivalve molluscs.  Specimens grow up to 1.3 m and can weigh up to 300 kg.  Despite its large size the Giant Clam only lives for about 100 years, far less than some other molluscs. It is a bivalve mollusc, meaning it has two shells, like mussels, razor shells and scallops. It feeds on tiny floating animals and plants as well as the sugars produced by the single-celled creatures called Zooanthellae that live in the Clam's body.