Could important clues to extraterrestrial life be hiding away in an obscure lake in Mexico? NASA researchers think so:

The network of 170 cactus-ringed lagoons around the town of Cuatro Cienegas have intrigued evolutionary biologists for decades because their fish, snail and turtle species rival the Galapagos Islands in their uniqueness.

Scientists from NASA's Astrobiology Institute have begun studying the lakes' ancient formations called stromatolites -- rock structures formed by layers of algae that trap silt. Conditions within the stromatolites are similar to those that prevailed on Earth for more than 2 billion years before the dinosaurs evolved.

Since the conditions in these lakes closely resemble the primitive Earth, it's thought they could provide insights into what conditions to look for on other planets.