Family Placospongiidae Gray, 1867

Diagnosis. Placospongiidae with tylostyles as megascleres and selenasters or amphiaster-like sterrasters as primary microscleres, forming polygonal cortical crusts. Cortical plates separated by contractile ectosomal pore grooves bearing ostia and oscula. Tylostyles in tracts radiating from the base toward the surface and supporting the margins of the cortical plates. Accessory microscleres include spirasters, spherasters, and spherules (Rützler & Hooper 2000).