I watched a digging project today where a worm ended up getting cut in half... of course I thought instantly about being told when I was younger that worms regenerate. You probably also were told at some point that an earthworm will regenerate into two new worms if it's cut in half.
This is only partially true. Earthworms have a distinctive head and tail. The head of a worm is always located on the end closest to the swollen band, called the clitellum. If an earthworm is split in two, it will not become two new worms. Instead, the head of the worm MAY survive and regenerate its tail if the animal is cut behind the clitellum (on it's tail). The original tail of the worm will not be able to grow a new head (or the rest of its vital organs) and will not become a new worm.