Our largest and most common species of earthworm is not native to North America. Night crawlers stowed away with European settlers bringing their favorite plants. Since then they've spread everywhere people have gone.
Earthworms have no teeth.
That doesn't stop them from eating just about any dead organic matter they come across. They also swallow soil as they burrow. The microscopic animals in each bite of soil become worm food, too. An earthworm's gut is a great place for bacteria to grow. Earthworm castings add more bacteria back to the soil than the worm eats.