Testaceous

Part of speech: adjective (a.)

1. Of or pertaining to shells; consisted of a hard shell, or having a hard shell.

2. Having a dull red brick color or a brownish yellow color. 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.