For 220 million years they have roamed the seas, denizens of the bustling coral reef and the vast open ocean. Each year, some emerge from the pounding surf onto moonlit beaches to lay their eggs. Throughout human history, we have revered them, used them, and worked to protect them, but we have only begun to understand these ancient, iconic creatures. Now, with all five of the sea turtle species in the U.S. threatened or endangered, knowledge is more crucial than ever.