Subterranean habitats are discrete, geographically replicated, ecologically simple and selectively similar habitats. Animals that successfully colonized these lightless environments were subjected to similar selective pressures and are therefore part of a large-scale natural experiment. As such, they are ideal for studying ecological and evolutionary processes. We appreciate having many of these natural laboratories in our backyard. Subterranean animals serve us as precious models for investigating fundamental questions about how biodiversity originated and how it should be protected.