Roundworms are parasitic worms that lay their eggs in the intestines and lives there. Roundworms can be found worldwide. The body of a roundworm is long and narrow. The cuticle is basically the worm's skeleton. It's the closest thing to a skeleton. Roundworms use the cuticle for movement. These worms have very long muscles underneath it's epidermis. These muscles are all aligned in a specific way so the body can bed its body from side to side.