Holopsamma

Char. Arenaceous sponges without fibre, whose composition consists of foreign microscopic objects (sand, fragments of sponge-spicules, Ac.) diffused in the flakes of the parenchymatous sarcode; traversed by the canals of the excretory system; assuming a variety of sponge-like forms, perhaps chiefly massive, in which respectively the surface may consist of the pore dermal membrane under any of the forms above mentioned, that is, simple, continuous, and smooth, or rendered more or less uneven and interrupted by the presence and projection of the sandy element above the common level.