Worms have evolved over millions of years into fast and efficient natural composters. Each worm eats and digests up to half its own body weight in waste every day, greatly reducing its volume. As a result the worms produce high quality compost.
Organic matter eaten by earthworms consists of rotting plant material and animal parts. They also eat soil harmful micro-organisms such as bacteria, fungi, and nematodes. Earthworms will feed on roots or other parts of plants that have been decayed by other organisms.
Earthworms are generally found in the top 10 or so few centimetres of the soil. They breath through their skin and therefore need a moist environment, so if the soil dries excessively, they will burrow deeper. (Up to 2 metres) They are basically nocturnal - coming to the surface at night when temperatures are lower and humidity higher. Sandy and acidic soils are their least favourite habitats.