The ground beneath us is alive, very alive. A single gram of soil (about a fifth of a teaspoon) can contain thousands of species of bacteria, and millions of individual cells. It might also be packed with fungi, microscopic worms, and other strange creatures like tardigrades and rotifers.

A new atlas, released Wednesday at the United Nations Environment Assembly in Nairobi, attempts to map this biodiversity around the world.

“When we think about biodiversity, we usually think about plants and animals,” says Alberto Orgiazzi, a soil biologist with the European Commission’s Joint Research Centre and one of the principal authors. “But there’s a huge world of organisms under our feet.” Those organisms play important, but largely unappreciated roles in agriculture and natural