Miraculous things happen to the desert when it rains – everything changes from brown to green and organisms that have not been seen for months make a brief emergence from underground lairs. In fact, even the desert’s soil turns visibly green following the rare desert rain, as hidden filaments of photosynthesizing cyanobacteria suddenly hydrate. Lying a few millimeters deep, these primitive prokaryotes quickly glide upward, migrating en mass to the surface for an hour or so of light exposure until the dirt begins to dry. Then, just as suddenly, they return again to the subsurface, where they begin the long wait for the next rain.