Porifera
All members of the Porifera phylum lack a distinct excretory system. Instead, these organisms rely on a water flow system to remove waste materials. In Porifera waste products such as ammonia diffuse into cells as water follows through its body. Archeocytes are used to remove the waste particles that could block the ostia through the mesohyl and dump them into the outgoing water current, while some members of the phylum incorporate them into their skeletal structure.