Earthworms are extremely beneficial to gardeners and growers by making the soil more fertile. An earthworm literally eats its way through soil and decaying vegetation. As it moves about, the soil is turned, aerated, and enriched by nitrogenous wastes. (In fact, English naturalist Charles Robert Darwin once calculated that a single earthworm could eat its own weight in soil every day.) Much of what is eaten is then excreted on the Earth’s surface in the form of “casts.” The worms then rebury these casts with their burrowing process.