Spongilla is a genus of freshwater sponges in the family Spongillidae found in lakes and slow streams. Sponges of the genus Spongilla attach themselves to rocks and logs and filter the water for various small aquatic organisms such as protozoans, bacteria, and other free-floating pond life. Unlike marine sponges, freshwater sponges are exposed to ...
• (n.) A genus of siliceous spongea found in fresh water.
sponge genus that includes the freshwater sponge (q.v.) species.
Spon·gil'la noun [ New Latin , dim. of spongia a sponge.] (Zoology) A genus of siliceous spongea found in fresh water. 
The spongilla is a member of the demospongia class.