See text Terebratulids are one of only three living orders of articulate brachiopods, the others being the Rhynchonellida and the Thecideida.
Terebratulids typically have biconvex shells that are usually ovoid to circular in outline.
The lophophore support is loop shaped in contrast to the spiralia of similar looking spiriferids.
Terebratulids are also distinguished by a very short hinge line, and the shell is punctate in microstructure.
Early genera were almost circular to elongate-oval, with smooth or finely costate shells.