 The adult maximum size of living species of bivalve ranges from 0 @.@ 52 mm ( 0 @.@ 02 in ) in <unk> maya , a nut clam , to a length of 1 @,@ 532 millimetres ( 60 @.@ 3 in ) in <unk> <unk> , an elongated , burrowing shipworm . However , the species generally regarded as the largest living bivalve is the giant clam Tridacna gigas , which can grow to a length of 1 @,@ 200 mm ( 47 in ) and a weight of more than 200 kg ( 441 lb ) . The largest known extinct bivalve is a species of <unk> whose fossils measure up to 3 @,@ 000 mm ( 118 in ) in length . 
