The Sponges usually known as Porifera (pore bearers) are aquatic filter feeders. The sponges consist of structural materials (spongin, spicules) which are usually made of calcium carbonate and/or silica. These structures forms their skeletal materials giving their body a thin sheet of cells over a frame (skeleton). As invetebrate and at the unicellular level of organization, Sponges lack muscle.
