Fossils of the earliest "modern-looking" crabs were discovered in tree amber, estimated by scientists to date back 100 million years – the most complete crustacean fossil ever preserved in amber. According to a study published Wednesday in the journal Science Advances, the discovery rewrites crustacean history, providing evidence that the miniaturized crabs (they're half the size of a thumbnail) may have briefly left their marine homes to climb a tree back during the Cretaceous period. The ancient crustacean was named Cretapsara anthanata, and its discovery is meaningful in the evolution of crabs because earlier fossils have indicated crabs started to crawl out of the water 50 million to 75 million years ago. But the discovery of cretapsara means land-moving crabs could've migrated out of water as far back as 125 million years ago. The study was a collaboration between Harvard and the China University of Geosciences. 📷: Image by Lida Xing, provided by the Department of Organismic & Evolutionary Biology at Harvard University