Diagnosis. Small, often symmetrical sponges, with radiating supporting processes and basal root adaptations for those living in soft sediments. Mostly deep water species. Axial skeleton composed of monactinal or diactinal megascleres, from which radiating extra-axial tracts diverge to lateral processes. Microscleres include (an)isochelae, sigmas, forceps, micro(subtylo)styles (microspined, spear-shaped in a few cases), and trochirhabds. Considerable reduction, to a complete loss of the choanocytes associated with an adaptation to carnivory, preying on relatively large food items (modified from Hajdu & Vacelet, 2002).