Where is the clitellum located and what is it used for?

The clitellum is a thickened, glandular section of the body wall found in certain annelids, particularly earthworms. It is typically located in the anterior (front) third of the worm's body. The clitellum plays a crucial role in reproduction; it secretes a mucus ring that helps in the formation of a cocoon for fertilized eggs, facilitating safe development outside the parent's body.