Each ring or segment on the worm has tiny bristles which help the creature move along the ground or burrow through the soil. There are hundreds of species of earthworms around the world - some measure only about one inch long. The giant earthworm of Australia is no garden variety worm. That last one was from Aristotle. Hey, it wouldn't be much of a world without earthworms.
Worms are long, thin digestive tracts that ingest large amounts of dirt.
As a result of their tunneling, worms break up the soil, providing oxygen for roots of plants. Worms help the soil hold more water. Worms clean up dead organic matter by eating it and turning it into castings, which may be the world's best fertilizer. Basically worms manufacture topsoil. Naturalist Peter Farb writes that worms pass more than 40 tons of castings per acre of territory.