softshell Definition

any of a family (Trionychidae) of freshwater carnivorous turtles that have sharp claws and mandibles and a flat round shell covered with soft leathery skin instead of with horny plates —called also soft-shelled turtle

having a soft or fragile shell especially as a result of recent shedding

an elongated clam (Mya arenaria) of the east coast of North America that has a thin friable shell and long siphon and is eaten especially when steamed —called also soft-shelled clam, steamer