How many underground creatures are there in the world?

The exact number of underground creatures in the world is difficult to determine, as many species remain undiscovered. Estimates suggest there are potentially millions of species, including various insects, worms, fungi, and microorganisms living in soil and subterranean environments. Researchers continue to explore these habitats, revealing new species and the complexity of underground ecosystems. Overall, the biodiversity of underground creatures is vast and largely unexplored.