Marine Biodiversity » Marine Sponges » Calcarea » Calcarea Classification » Subclass Calcaronea

Definition: Hemispherical or conical growth forms; ectosomal skeleton contains sagittal triradiates, tuning fork spicules and quadrirradiates, some of which also extend into the mesohyl; basal skeleton composed of spherulitic units of calcite, fused together to form hemispherical mass, each unit with terminal osculum surrounded by collars of quadriradiates; living tissue penetrates into the calcitic mass only for short distances, and free spicules in the mesohyl include microdiactines; triradiates, with a rudimentary fourth ray, also occur at the base of living tissue; nuclei of choanocytes are apical; larvae are amphiblastula.

Scope: A single genus.

Reviews: Nil.

Genera:
Petrobiona Vacelet & Lévi, 1958 (type species: Petrobiona massiliana Vacelet & Lévi, 1958) - as for family.