Acoela is a group of simple, soft-bodied marine animals that belong to the phylum Platyhelminthes. They are primarily found in shallow waters and are known for their flat, worm-like bodies. Acoelans lack a true body cavity and have a simple digestive system, often feeding on small organic particles and microorganisms. These organisms are important for understanding evolutionary biology, as they are considered to be among the most primitive members of the bilaterian lineage. Acoela exhibit a range of body forms and sizes, and their study can provide insights into the early development of more complex animals.