The electric eel, or plumber's snake, spins a flexible steel cable fitted with blades or corkscrew heads. As it rotates, it chews a path through paper, roots and debris.
Eels are quick and effective for softer blockages, but they typically cut a hole through the obstruction rather than cleaning the pipe wall, so regrowth or re-blockage is common when the underlying cause remains. Cables can also damage already-fragile pipes, which is why a camera check afterwards is good practice.