To lay your eyes on a fossil is to take a profound glimpse at a time long since passed. Fossils are a beautiful phenomenon which are the remains of prehistoric organisms that are petrified and molded into rock. These amazing impressions can be as old as 3.7 billion years, and as recent as a few million years old. When kids crack open a rock and find a fossil, is it really a rock? Or is it a time capsule encapsulating an entire species? We hope you appreciate these amazing fossils as much as we do, here are 20 fossil photos that will take you back in time. And if you enjoy these check out some more ancient photos showing various animals before they went extinct.