What is coelm?

Answer 1

It is a body cavity (or space) on addition to the gut/digestive system.

Answer 2

"Coelom" is a fluid-filled body cavity in some animals, located between the gut and the outer body wall. It acts as a space for organs to be suspended and protected, as well as facilitating movement and expansion of internal organs. This cavity is present in organisms such as annelids, mollusks, and vertebrates.