Flat worms are invertebrates and usually have a flat body that is soft and fleshy. They are typically very small and can reproduce asexually or sexually. Their nervous system consists of two long cords made of nerve tissue.

There are about 20,000 known species of flatworms.

One example of a flatworm is Bedford's flatworm, also known as Pseudobiceros bedfordi. This species of flatworm has ruffles around the edges of its body.

Another example is the tiger flatworm, also known as Pseudoceros dimidatus. These flatworms live near coral reefs in warm waters.

http://animaldiversity.ummz.umich.edu/accounts/Platyhelminthes/

http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html