The word “worm” is almost uselessly vague, as it describes so many different animals. There are the segmented worms, a group that includes both the humble earthworm and the ornate Christmas tree worm. There are the aggressively carnivorous ribbon worms, the usually plant-sucking roundworms (but the parasitic hookworms and heartworms are also types of roundworms) and even slow worms, which are really legless lizards.
