Common name : paper nautiluses or argonauts

Aspect : the female secrete a thin, calcareous, paper-like shell to shelter its eggs and to regulate its depth of buoyancy. Shell with a contour resembling the nautilus; shell laterally compressed with tubercles in Argonauta argo, square-keeled with ribs in Argonauta hians; can reach 120-200 mm

Feeding : carnivorous predators adapted to a planktonic feeding (small pelagic prey such as heteropod, pteropod and sea butterflies, planktonic crustaceans, tiny fish larvae and shrimp); they form symbiotic or opportunistic associations with jellyfish (Phyllorhiza punctata) or salps (semi-transparent barrel-shaped marine animals often mistaken as jelltfish), using them as hunting platforms to ambush smaller prey such as comb jellies or commensal amphipods

Environment : worldwide in tropical and subtropical open oceans, with a cosmopolitan distribution from the Indo-Pacific to the Atlantic, at 0-100 m depth often accumulating near island arcs or beaches due to winds and currents