Penion maximus
Penion maximus is a species of very large predatory sea snail or whelk , commonly known as giant whelk or great whelk , a marine gastropod mollusc in the family Buccinidae , the true whelks . 
<triplet> whelk <subj> sea snail <obj> subclass of <triplet> gastropod <subj> mollusc <obj> parent taxon