Porifera
Porifera are often called sponges. They are categorized by a special feeding system in which water is drawn through pores in the outer wall. Cells filter out nutrients form the water.
Sources:
http://www.ucmp.berkeley.edu/porifera/porifera.html
http://people.eku.edu/schusterg/bio542/porifera.htm
http://www.ucmp.berkeley.edu/porifera/porifera.html
http://people.eku.edu/schusterg/bio542/porifera.htm