Like a lugworm. Nereis taxonomically belongs to the phylum Annelida, class Polychaeta, order Wanderers, and family Nereisidae, and is commonly known as sea worms, sea maggots, sea centipedes, and sea locusts. A type of animal bait. The body is clearly segmented, and both sides of the body segments protrude into warts with bristles for movement. About 10 cm long. It lives in mud and sand, and can swim during the reproductive season or when looking for food at night (Baidu Encyclopedia).