The identification of fossil molluscan larvae can enhance the biostratigraphic utility of fossil mollusks. Larval and juvenile mollusks are commonly preserved in the fossil record and are often more abundant than adults per unit volume of sediment and more diverse than adults for equal numbers of individuals. Larval shell morphologies are species specific and usually possess characters sufficient for their identification.
An outcrop study in the Eocene of Texas suggests that larval mollusks may be less fades controlled and have wider geographic distributions than do their adult counterparts. Molluscan larval shells are common in cuttings from the Eocene interval of an east Texas well, and they provide a more refined stratigraphic correlation than is possible with foraminifera.