The King Rag Worm (Nereis virens) is a species of worm in the Nereidae family.
This large species usually grows to about 20cm in length, but large specimens can reach up to 40cm in length. This species has a proboscis which bears free teeth, and there are between 6 and 10 teeth on each of the jaws. There are between 100 and 175 segments on the long body. The adults of this species are green with a purple tinge, with a yellow border to the parapodia. This species can be as thick as a human thumb.