Sometimes the helmet shell has a midline ridge.

This species is in the subfamily Cassinae, the "helmet shells" and "bonnet shells", which feed on sea urchins.

It is commonly known as the bullmouth or red helmet shell, and also as the cameo shell.

Some helmet shells are carved into cameos, starting in Italy in 1820.

Sometimes the helmet shell has a mid-line reinforcement ridge, which strengthens it against impact.

It is the largest of all helmet shells.

The helmet shells of the world (Cassidae).

The initial process begins with the making of the helmet shell using a vacuum forming machine and a metal mould.

Shells (strombus gigas renowned for their flesh, helmet shell, clam, whelks, etc.)

Semicassis thomsoni is a species of large predatory sea snail, a marine gastropod mollusc in the family Cassidae, the helmet shells and their allies.