Our planet’s soils contain enough of the subterranean fungi that sustain plant life and help regulate the climate to stretch from the Earth to the sun almost three-quarters of a billion times, a groundbreaking new study has found.

Arbuscular mycorrhizal fungi are networks of tubular cells called hyphae that sustain life on Earth by forming critical partnerships with more than 70% of plants. The networks, which have been forming for about 475 million years, provide nutrients and water in exchange for the carbon produced by the plants, and help to regulate the climate by drawing carbon into soils.

And yet, despite their importance, very little is known about their distribution and density across natural ecosystems.…