The basic body plan of an earthworm is a tube, the digestive system, within a tube, the muscular slimy, moist outer body. Most earthworms are decomposers feeding on undecayed leaf and other plant matter. They attain full size in about one year, sometimes sooner. Scientists predict that the average lifespan under field conditions is 4–8 years, still most garden varieties live only one to two years.
They are found around the world.