A marine mollusc, of the family Nautilidae native to the Pacific Ocean and Indian Ocean, which has tentacles and a spiral shell with a series of air-filled chambers, of which Nautilus is the type genus.
A kind of diving bell that sinks or rises by means of compressed air.
A pelagic octopus of genus Argonauta, found in warm seas, whose females produce a paper-thin egg case resembling a shell into which she deposits her eggs.