nautilida

Chambered Nautilus by tinybubble Nautilus (from Greek ναυτίλος, ‘sailor’) is the common name of pelagic marine mollusks of the cephalopod family Nautilidae. It comprises six living species in two genera, the type of which is the genus Nautilus. Though it more specifically refers to species Nautilus pompilius, the name chambered nautilus is also used for any species of the Nautilidae. (Wikipedia)