American evolutionary biologist Toby Kiers has been awarded the prestigious Tyler Prize for Environmental Achievement, often dubbed the 'Nobel for the environment,' for her groundbreaking work on mycorrhizal networks. These underground fungal webs, fundamental to global nutrient cycles and climate regulation by sequestering around 13 billion tonnes of carbon annually, were previously underestimated. Kiers has brought this unseen ecosystem to light, emphasizing their role as critical environmental components. Through her research, including a global Underground Atlas and innovative imaging techniques, Kiers has advanced the understanding of these networks, highlighting their 'biological marketplace' dynamics where fungi exchange nutrients with plant roots. Her work underscores the urgency of conserving underground biodiversity, with most crucial fungal diversity hotspots lying outside protected areas. To bolster conservation efforts, she co-founded the Society for the Protection of Underground Networks (SPUN) and is launching an 'Underground Advocates' program to equip scientists with legal tools for preservation.