are deep-water animals that form large billowing growths up to ten feet in diameter and almost seven feet high. There are about 5000 sponge species known across the world. Sponges are found mostly in marine water, but around 150 species live in fresh water. They can also be found in inlets, on rock walls and ledges at depths of 100 feet and deeper. In the sponge cavities, you may find many other animals such as rock fishes and a variety of invertebrates. It provides a home for a number of small marine plants, which live around their pore systems.