The phylum Porifera or sponges all have the similar characteristics, they are multi cellular organisms, and most life sedentary lives. Sponges do not have do not have nervous, digestive of circulatory system. Instead they rely on a constant stream of water to supply them with food, oxygen, and to remove wastes. The reason sponges have different shapes is because different shapes are better for filtering water.
Spongebob was a lie, sponges don't have hearts.