mollusc, mollusk, shellfish - invertebrate having a soft unsegmented body usually enclosed in a shell

Cephalopoda, class Cephalopoda - octopuses; squids; cuttlefish; pearly nautilus

chambered nautilus, pearly nautilus, nautilus - cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions

dibranch, dibranchiate, dibranchiate mollusk - cephalopods having two gills

octopod - eight-armed cephalopod lacking an internal shell

decapod - cephalopods having eight short tentacles plus two long ones