Craniidae

The Craniidae are a family of brachiopods (lamp shells). Although it belongs to a subdivision called the inarticulata which have shells where the mineral content consist of calcium phosphate, the Craniidae have shells that consist of calcium carbonate. Other special characteristics of this family are that no outgrowths are developed to form a hinge between both valves, nor is there any support for the lophophore. As adults, craniids either lived free on the ocean floor or, more commonly, were attached to a hard object with all or part of the ventral valve. All other brachiopods are supposed to have a stalk or pedicle, at least as an adolescent, but in craniids a pedicle is not known from any development stage.