Class Spongilla (Freshwater sponge) 
Sponges are delicate in structure, growing as encrusting or branching masses; usually appear greenish because of the algae that live on them. Freshwater sponges may attain a volume of more than 2,500 cubic centimeters (150 cubic inches). Spongilliflies can sometimes be found in the canals or the outside of sponges. FilterersS-VL (U)(S/F)