In 2003, an army of 350 scientists and volunteers swept out across Central Park. Their mission, called a BioBlitz, was to find as many species as possible over the course of 24 hours. At the end of the day, they had compiled a catalog of 836 species of plants and animals.

It’s impressive that Central Park–an 843-acre island in an ocean of Manhattan concrete–can play host to so many species. But that’s hardly a complete inventory of the biodiversity of the place. Along with its plants and animals, Central Park is home to invisible wildlife too.

The ground swarms with invertebrates, fungi, and a wealth of microbes. This underground diversity–especially the microbes–has been very hard to explore, not just in Central