Beneath Your Feet: The Fungal Network Covering 62 Quadrillion Miles

There’s an invisible city beneath every patch of grass you walk on, and scientists have just finished mapping it. Researchers studying fungal networks—the underground filaments that connect plants in what’s known as the“wood wide web”—discovered something staggering: in just the top 15 centimeters of soil, these networks stretch approximately 62 quadrillion miles long. To put that in perspective, if you spun all those filaments into a single thread, it would travel from Earth to the Sun and back a billion times over.

This isn’t just trivia for fungi enthusiasts. The fungal networks form a critical biological partnership between plants, fungi, and microorganisms. The plants provide sugars through photosynthesis, while the fungi—specifically arbuscular mycorrhizal fungi—reach deep into the soil to deliver water and essential nutrients like phosphorous and nitrogen that plant roots can’t access on their own. It’s a mutually beneficial arrangement that’s been quietly running one of Earth’s most important systems for millions of years.

But here’s where it gets concerning: the research, published last July, also revealed that less than 10% of the densest fungal clusters are currently protected. The densest networks exist in grasslands and wetlands rather than forests—places like the Anatolian steppe, the Tibetan plateau, the North American Prairie, the Everglades, and the Sudd wetlands in Africa. Where human agriculture is intensive, these critical fungal networks are dramatically reduced. Scientists at the Society for the Protection of Underground Networks (SPUN) created an interactive map to visualize this hidden infrastructure globally, hoping to push for stronger conservation efforts.

Of the more than 8,000 known fungal species participating in the wood wide web, virtually none have been assessed for endangered status by international conservation authorities. It’s a blind spot that’s hard to ignore once you realize what’s at stake. This fungal network is directly tied to a plant’s carbon storage potential—something that matters enormously in our current climate moment. Protecting these underground systems isn’t just about preserving nature for its own sake; it’s about maintaining the biological machinery that helps regulate the planet itself.