Sponges don't have symmetry in any way and have a multicellular structure. They all attach to something to live when mature and may reproduce sexually or asexually. They also have no nervous system, and live in aquatic habitats.

There are about 5,000 known species of sponges.

One example of a sponge is the stove-pipe sponge, also known as Aplysina archeri. These sponges take on the shape of tubes and can grow to be three inches thick.

Another example is the brown tube sponge, also known as Agelas conifera. These are found mostly in the Caribbean and sometimes in Florida.
http://www.earthlife.net/inverts/porifera.html

http://www.mcwdn.org/Animals/Sponges.html