Illustration of life on the forest floor. Contents: Clumps of moss with sporophytes, green; carpenter ants (Camponotus pennsylvanicus), on stump; mites (Trombicula sp.), small red; entomobryid springtails (Orchasella ainsliei), lower center; pseudoscorpion (Chelifer sp.), to right of springtails; pillbug (Armadillidium vulgare), lower right; snail (Helix sp.), above pillbug; and red oak (Quercus rubrum), leaves. Narrative: Scientists have calculated that one acre of forest soil holds a billion nematode worms, a million earthworms, and billions of other animals, not counting bacteria which would outnumber all other organisms. It has been estimated that the topsoil of one typical acre of forest holds over 100 tons of living plants and animals. Many of these organisms are decomposers which break down and transform dead material into usable nutrients for living plants and animals.