Heterocyathus Milne-Edwards & Haime, 1848

Diagnosis.

Corallum free and usually encapsulating a gastropod or scaphopod shell inhabited by a sipunculan worm. Costae at lateral theca distinct and either equal or unequal in thickness. At base costae transform into granulations. Lower part of corallum shows a relatively large worm opening (occasionally two) and several small pores.

Type species.

Heterocyathus aequicostatus Milne-Edwards & Haime, 1848, by subsequent designation (Milne-Edwards & Haime, 1850b).