Molluscs - Nautiloids

The Molluscs compose the large group of invertebrate animals known as the Mollusca. Around 85,000 extents species of Molluscs are recognised.
Molluscs not just in size and in anatomical structure, but also in behaviour and in habitat too are a very diverse group that includes Chitons, Scaphopods, Bivalves, Gastropods and Cephalopods. The soft body is rarely preserved, so Molluscs are classified by their shell structure.

Nautiloids are primitive, marine cephalopods that possess a shell. Straight (like an Orthoceras), curing, or loosely or light coiled calcium-carbonate shells, divided into a chambered phragmocone and a living chamber. The chambers are connected by a tube (siphuncle)

Nautiloids had heads with well-developed eyes, and gasping tentacles. They swam by squirting water out of the body cavity.