The sponges reproduce either sexually or asexually. When they reproduce sexually, they usually cross-fertilize. Eggs and sperm unite to make a free-swimming larva that settles on a different surface. Asexually, the sponge produces small, internal buds called gemules . These gemules each produce a new sponge.
Sponges can also reconstitiute themselves if their cells are separated into a suspension.
The anatomy of a sponge. What the skeleton of a sponge looks like.