Terebratulids are one of only five living orders of articulate brachiopods, the others being the Rhynchonellida, Thecideida, Craniida, and Lingulida. The name may be derived from the Latin "terebra", meaning "hole-borer". The perceived resemblance of terebratulid shells to ancient Roman oil lamps gave the brachiopods their common name "lamp shell". Terebratulids typically have biconvex shells that're usually ovoid to circular in outline. They can be either smooth or have radial ribbing. The lop… (More on Terebratulida)