Soft-shell

a.
  1. Having a soft or fragile shell.
    2. Soft-shell clam (Zoöl.),
    the long clam. See Mya.
    Soft-shelled crab . (Zoöl.)
    See the Note under Crab, 1.
    Soft-shelled turtle . (Zoöl.)
    Same as Soft tortoise, under Soft.