Stromatolites

The history of life is recorded in stone, not by ancient civilizations, but by microorganisms. Over 3.5 billion years ago, these tiny organisms left their mark through stromatolites and microfossils. But how can something microscopic create visible structures? How do we know these fossils are from ancient microorganisms? Luckily, their modern descendants still exist, and living stromatolites can be found if you know where to look.