All soil life has a hand in creating the world, or worlds, of the soil.
Though fungi and bacteria do most of the work, they have help. Earthworms literally eat their way through the soil, which on its way through their lengthy guts is refines, enriched, and mixed with the proceeds of leaves that the worms have dragged into their burrows and eaten. Unlike cats, who like to bury their feces, earthworms go to some trouble to deposit theirs on the surface of the ground. Known as castings, these deposits are fine, dark, and fabulously rich, having twice the calcium, thrice the magnesium, five times the nitrogen, seven times the phosphorus, and eleven times the potassium of the surrounding soil. There is also a fabulous lot of them.