Worms are invertebrates that live on Planet Earth, Monster World and Mobius. The most commonly seen is the earthworm that live underground and are a tasty treat for most birds.
- Worms on Mobius seem to be centred in the Underzone and very rarely venture to the outside world. When they do, such as when Zeg went outdoors, they must make sure they are not followed back so as to not compromise their secrecy and safety. They are a mining race and love to eat mouldcake.
- There are Badniks that resemble worms, such as the obviously named Sandworm. Caterkillers are also quite like worms, particularly since the term 'worm' also covers such creatures as caterpillars.
- A giant worm appeared in a Monster World Smuggler's Tunnel which Shion had to fend off with his sword and magic.