If you cut an earthworm in half, both pieces will regenerate and become two complete worms.
When an earthworm is cut, only the head end (with the brain and major organs) can regenerate, growing a new tail. The tail end cannot regenerate a head and dies. Some worms have remarkable regenerative abilities, but earthworms specifically don't become two worms from one cut.
Reception
Sources
- Smithsonian Magazine: Worm Regeneration REFERENCE
- Scientific American: Regeneration REFERENCE