When mating, two worms join together with heads pointing in opposite directions. Sperm is passed from one worm to the other and stored in sacs. Then a coocon forms on each of the worms on their clitellum. As the coocons are coming off eggs and sperm are deposited to the coocon. When the coocons are totally off the fertilization takes place. the coocons are much smaller than a grain of rice. Each coocon could have 1-5 worms.