nautilus (n.)
marine cephalopod, c. 1600, from Latin nautilus, in Pliny a kind of marine snail (including also squid, cuttlefish, polyps, etc.), from Greek nautilos "paper nautilus," literally "sailor," from nautes "sailor," from naus "ship" (from PIE root *nau- "boat"). The cephalopod formerly was thought to use its webbed arms as sails.