Juergen Freund / Chambered nautilus (Nautilus pompilius) with red whip coral. Osprey Reef, Great Barrier Reef, Queensland, Australia.

Juergen Freund / Boat at surface tracking Nautilus movements with a mobile receiver, off Queensland, Australia, 2007

Juergen Freund / Chambered nautilus (Nautilus pompilius) with radio transmitter, Indo-pacific

David Shale / Deepsea heteropod mollusc (Carinaria lamarcki) from between 188m and 74m, Mid-Atlantic Ridge, North Atlantic Ocean

David Shale / Deepsea heteropod molluscs (Carinaria lamarcki) from between 188m and 74m, Mid-Atlantic Ridge, North Atlantic Ocean

Juergen Freund / Portrait of Chambered Nautilus {Nautilus pompilius} Underwater, Papua New Guinea

Juergen Freund / X-ray of the shell of the Pearly / Chambered nautilus {Nautilus pompilius} showing the internal chambers of the shell.

Fred Bavendam / Chambered Nautilus (Nautilus pompilius), Coral Sea, Australia

Norbert Wu / Chambered Nautilus (Nautilus pompilius) comes up from great depths at night to shallows, Palau

Fred Bavendam / Paper Nautilus (Argonauta nodosa) is actually a pelagic Octopus, females make the parchment-like shell to carry incubating eggs, South Australia

Flip Nicklin / Chambered Nautilus (Nautilus pompilius) portrait, North America

Juergen Freund / Two Pearly nautilus {Nautilus pompilius} Sulu-sulawesi seas, Indo-pacific. Fills shell with water to sink and expells water to rise, lateral movement by jet propulsion