In your life, you’ve probably seen tubes, sacs, purses, balls, vases, and trees thousands of times. However, have you ever seen an animal that looked like one of these objects? Sponges, even though they are very simple animals, may look like, or resemble, many things. Sponges can be any color from bold shades to pastels. They can be very small or very large. In your hands, some may sting, be soft, or even feel like glass. Often, sponges are classified because of their shape, colors, or other physical things.

To make things a little bit more simple to understand, scientists have put sponges in three basic groups. These groups are used to describe what a sponge looks like. The first type is the most simple. The third type is the most complicated. All of these types do have certain parts that are found in all sponges.

To sum up the purpose of a sponge, it is to filter water. The sponges take in water through ducts and holes in their skin known as "pinacocytes". When the water passes through these holes, it goes into the sponge. Another similar part on the outside of all sponges is the osculum. The osculum is a hole, usually on the top of the sponge, that pushes the water out of the sponge along with wastes, things that the sponge has used up and doesn’t need. Also, a very important part that all sponges have are spicules. Spicules are tiny needles that stick out from the skin of the sponge. They act like a skeleton. Spicules keep animals, like fish, from eating the sponge.

The three main types of sponges are:

Asconoids	-These are the simplest of the sponges. Usually, they come from sponges that lived long ago. They are about 4 inches or 10 cm. Also, they usually look like a slender sack or tube.
Syconides	-In comparison to asconoids, these are slightly larger, thicker, and more complex. Their holes make rows on a smooth surface. Also, they are shaped like tubes.
Leuconides	-Leuconides are the largest of all the sponges. They are the best constructed for movement. In five minutes, they filter their own weight in water.