Conchifera

Conchifera is a subphylum of the phylum Mollusca. It comprises all of the shell-bearing classes of molluscs, including the snails, clams, tusk shells, ammonites, monoplacophorans, and so on. The other one is Aculifera.

This taxonomic term is used mostly by paleontologists, and not by scientists who study the living molluscs.