Veliger n. : Any larval gastropod or bivalve mollusk in the state when it is furnished with one or two ciliated membranes for swimming.

Example:
A fertilized oyster egg develops into a free-swimming larval stage called a Veliger...?

Taxonomy
veliger, veliger larvae, adult, bivalves, gastropods, velum, larva, larval stage, stage, the egg, trochophore, metamorphose, body, juvenile, feed, adult shells, free encyclopedia, juvenile stage.

Defination from the web:
veliger is the planktonic larva of many kinds of marine and fresh-water gastropod molluscs, as well as a number of bivalves (in genus Dreissena) ... During this period the veliger grows and also develops the organ systems necessary for the benthic life of a juvenile. ...