There is a place in northern Chile, 3,500 meters above sea level in the Andean Altiplano, where almost nothing survives. The Salar de Pajonales is a salt flat of savage extremes temperatures swinging from −23°C to 26°C, solar radiation among the highest measured anywhere on Earth, annual rainfall that barely registers, and winds that rip across the surface at over 100 kilometers per hour. And yet, life is there.

There is a place in northern Chile, 3,500 meters above sea level in the Andean Altiplano, where almost nothing survives. The Salar de Pajonales is a salt flat of savage extremes temperatures swinging from −23°C to 26°C, solar radiation among the highest measured anywhere on Earth, annual rainfall that barely registers…

In the deeper layers of the gypsum, researchers found the glassy remains of microscopic algae along with preserved filamentous cell structures and tell-tale chemical signatures of ancient photosynthesis. These are fossils, entombed in crystal during a wetter period in the salt flat’s history…

If gypsum can preserve biosignatures for thousands of years on Earth under conditions this extreme, it raises a tantalizing possibility that similar deposits on Mars might be holding onto evidence of ancient life…