Testaceous

a.
  1. Of or pertaining to shells; consisted of a hard shell, or having a hard shell.
  2. (Bot. & Zoöl.) Having a dull red brick color or a brownish yellow color.
    3. Testaceous animals (Zoöl.),
    animals having a firm, calcareous shell, as oysters and clams, thus distinguished from crustaceous animals, whose shells are more thin and soft, and consist of several joints, or articulations, as lobsters and crabs.