1) Family fissurellidae 2) Mollusk family 
Fissurellidae, common name the keyhole limpets and slit limpets, is a taxonomic family of limpet-like sea snails, marine gastropod molluscs in the clade Vetigastropoda. Fissurellidae is the only family in the superfamily Fissurelloidea. The distribution of fissurellids is world-wide, from cold waters to tropical waters. ==Habitat== Fissurellids li...
Fissurellidae (keyhole limpets) is a family of gastropod molluscs resembling the limpets in appearance and habits, but differing in structure. They are generally too large for their shell, and so it appears that the shell is rudimentary.
[n] - marine limpets
family Fissurellidae noun marine limpets