Flame cells are the excretory system of flatworms. Flatworms do not have a true circulatory or respiratory system, and so they rely on a network of flame cells to filter out waste products and excess water from their bodies. These specialized cells are located on the sides of the flatworms' bodies and contain tiny hair-like structures called cilia. The cilia beat in a coordinated manner to create a current of fluid that draws waste products and excess water into the flame cells. The waste products are then eliminated from the body through tiny openings called nephridiopores.