A science project with sponges
You can check out sponges for yourself – go to any Whole Foods or other natural health products store and they’ll have real natural sponges there for people to clean themselves with.
Some questions to ask yourself
What does the sponge feel like? Is it heavy or light? Does it smell bad? What we think of as a sponge is really the skeleton of a sponge – the calcium-based or collagen-based remains of the sponge’s support structure. See the holes so that each cell can get air and food? Is this sponge radially symmetrical? Can you find the opening of the sack-like shape, where it pulls in water and pushes water out again?