Echinocardium cordatum Pennant, 1777
This is not a Mollusc. Other non-Molluscan Phyla (Echinodermata, Brachiopoda etc) have been included to help identify species that may be mistaken for Mollusca, but actually are not.
Echinodermata (Phylum) > Echinozoa (Subphylum) > Echinoidea (Class)
> Euechinoidea (Subclass)
> Spatangoida (Order)
> Loveniidae (Family)
> Echinocardium (Genus)
Widespread 3-300 metres, around New Zealand and Australia, north and south Pacific, the Atlantic, and Mediterranean, but discontinuously. Not found in tropical seas