👉 A flatworm is a type of worm that is characterized by its elongated body shape and a flattened, circular shell. Flatworms are found in various environments, such as freshwater bodies like lakes, rivers, and streams, and saltwater habitats like oceans. They are typically small in size and have an average length of about 0.2 to 1.5 cm (0.08 to 0.6 inch) and a diameter of around 3 to 4 mm (