If you’ve ever wondered how geologists know so much about ancient beaches and shallow oceans — from the paleoenvironment to the animals roaming around, the seasonality of the weather, and even the time of day when the ancient scene was preserved — they owe it all to the sand particles bound together by microbes, forming structures known as microbial mats. A planar microbial mat with scours of ripple marks on a Cambrian (left) and modern-day...
