Even in agricultural soils, more than a thousand arthropod legs support your every step. One cup of soil may hold as many bacteria as there are people on Earth. Bacteria and actinomycetes are exceedingly tiny. Yet, because of their tremendous numbers, they make up half the living biomass in some soils. The weight of all the bacteria in one acre of soil can equal the weight of a cow or two.
Actinomycetes have cells like bacteria, but grow as long filaments like fungi.
A teaspoon of farm soil may contain tens of yards of fungi. The same amount of soil from a coniferous forest may hold tens of miles of fungi. Nematodes are amazingly diverse. Twenty thousand species have been described, but it is thought that 500,000 species may exist. Five thousand soil species have been described.