bobbit worm

Eunice aphroditois (colloquially known as the Bobbit(t) worm) is an aquatic predatory polychaete worm dwelling at the ocean floor. An ambush predator, the animal buries its long body into an ocean bed composed of gravel, mud, or corals, where it waits for a stimulus to one of its five antennae, attacking when it senses prey. Armed with sharp teeth, it is known to attack with such speed that its prey is sometimes sliced in half. Wikipedia