Anywhere from 17 to 35 segments from the front of an adult worm is a thick band called the “clitellum.” The exact location varies for different worm species and families.
The clitellum produces a cocoon, in which the eggs and sperm are placed. For the common Lubricidae earthworm, eggs are deposited on segment 14, while the sperm is usually placed on segment 15.
The clitellum slips forward and off the “nose” of the earthworm. It forms a cocoon for the baby worms.
By the way, any adult worm can have babies.
See the orange band on this worm? That’s the clitellum, which forms a cocoon.
Photo: Mike Jeffords, University of Illinois