The annelids (Annelida, from Latin anellus, “little ring”), also known as the ringed worms or segmented worms, are a large invertebrate phylum, with over 17,000 modern species including ragworms, earthworms, and leeches.
Oligochaetes are full hermaphrodites and produce a ring-like cocoon around their bodies, in which the eggs and hatchlings are nourished until they are ready to emerge.