A flame cell is a specialized excretory cell found in simple invertebrates, including flatworms (Platyhelminthes), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system.
Flame cells function like a kidney, removing waste materials.
The beating of these flagella resemble a flame, giving the cell its name.
The tube opens externally through a nephropore, or, in the trematoda, into an excretory bladder.
The function of these cells is to regulate the osmotic pressure of the worm, and maintain its ionic balance.