Olivia Drake#THISISWHY Research Professor Ellen Thomas grasps a glass-enclosed sample of hundreds of microfossils, each a white fleck of limestone barely visible to the human eye. "The first time students look at these they say, 'they all look the same to me,' but in reality, they are all have very different shapes," Thomas says. "Even under a microscope, it can be difficult for a new eye to see the differences, but each species has its own shape; some have a much more open, light structure because they lived floating in the oceans close to the surface. Others have denser shells and lived on the bottom of the ocean,…
