Sea sponges don't look like animals. They don't have heads, arms, or legs. They don't have eyes or faces.
Sponges live their lives attached to rocks, plants, and other objects. Adult sponges don't move. Experts used to think they were plants. But they are animals.
They are some of the oldest animals on the planet. There are fossils of sponges that are 500 million years old.
Sponges can live for hundreds or even thousands of years.