nautilus

Etymology

From Latin nautilus, from Ancient Greek ναυτίλος (nautílos, “paper nautilus, sailor”).

noun

1. 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.
   He was still prepared to go on collecting all that life could offer, like a chambered nautilus patiently adding new cells to its slowly expanding spiral. 1956, Arthur C. Clarke, The City and the Stars, page 44
2. A kind of diving bell that sinks or rises by means of compressed air.