testaceous

adjective3

1. •
   Having a shell, especially one which is not articulated.

   • It has a very large head, in proportion to its body, all covered with a shell, like other testaceous Animals […] — 1665
2. •
   Of a dull orange or brownish colour, like brick.
3. •
   (no longer used) Pertaining to earthenware or baked clay.

   • [T]hey were burnt, or only baked in Oven or Sunne: According to the ancient way, in many bricks, tiles, pots, and testaceous works […] — 1658