They grow in still, clean water. Many thousands of individuals may encrust onto rocks, pipes, etc. There is only one family of fresh water sponges or Porifera . About 150 species live in ponds and lakes throughout the world. Larvae are free swimming but adults are brown or greenish globs from an inch to a dozen square feet in size.
Green sponges have symbiotic algae.
They eat microorganisms that get sucked in through their pores. A single sponge is actually a colony of animals like coral. Books These are the books that I own and that I used as references for this web page. A Guide to Common Plants and Animals of North American Ponds and Lakes by Dr. George K. Reid, Golden Press, 1967. A book chock full of information.