Spheciospongia Vesparium
(Sea Sponge)
All sponges have similar excretory systems. Cells absorb oxygen form the water through diffusion. Here, metabolic wastes, including ammonia and carbon dioxide, diffuse into the surrounding water. Because the ostia is an important part of every sea sponge, minerals can sometimes block the entrance. Archeocytes dump them into the water current to avoid a blockage.