The Bobbit worm, Eunice aphroditois, is a ferocious underwater predator. Armed with sharp teeth, it is known to attack with such speeds that its prey is sometimes sliced in half. Though they do vary in size, they have been recorded to grow up to nine feet tall.
Bobbit worm is a fantastic critter, one of the largest of all polychaetes (reaching 3 meters in length and thick as a bratwurst), with a colourful cuticle and armed with a pair of heavily toothed jaws that command respect. (via Deep Sea News)