Anaspidea

The clade Anaspidea, commonly known as sea hares(Aplysia species and related genera), are medium-sized to very large opisthobranch gastropod molluscs with a soft internal shell made of protein. These are marine gastropod molluscs in the superfamilies Aplysioidea and Akeroidea. For more information, visit the Wikipedia entry. Get back to Gastropoda
Aplysia sydneyensis