Healthy garden soil is ALIVE.

One teaspoon of compost may contain:

1 billion invisible bacteria
(20,000 to 30,000 species of them),
400 to 900 feet of fungal hyphae (thread-like structures), 10,000 to 50,000 protozoa, and 30 to 300 nematodes. Then there are algaes and slime molds, and arthropods (“insects” or “bugs”),
both visible and microscopic.

Paraphrased from Jeff Lowenfels and Wayne Lewis, Teaming with Microbes, Timber Press, 2010