A planarian is a type of flatworm belonging to the class Turbellaria. These simple, soft-bodied organisms are known for their remarkable regenerative abilities, allowing them to regrow lost body parts. Planarians are typically found in freshwater environments, such as ponds and streams, and they can also inhabit moist terrestrial areas. Planarians have a distinct, elongated shape and a head with two eye spots that can detect light. They feed on small organisms and decaying matter, using a specialized mouth located on the underside of their bodies. Their unique biology makes them a subject of interest in scientific research, particularly in studies related to regeneration and developmental biology.