Thecideida is an order of cryptic articulate brachiopods characterized by their small size and habit of cementing their ventral valves to hard substrates such as shells, rocks and carbonate hardgrounds. Thecideides first appeared in the Triassic and are common today.

Thecidium mediterraneum, A. natural size: B. section through shell (magnified)

Taxonomy

Order Thecideida

  • Superfamily Thecideoidea Gray, 1840
  • Superfamily Thecospiroidea Bittner, 1890