Nearly two decades after coming to the Hopkins Marine Station as an undergraduate in earth systems, Raphael D. Sagarin was again hunched over a tide pool identifying its briny inhabitants. His mentor, emeritus lecturer Chuck Baxter, stood on a nearby outcropping and called out helpful advice. It was a drippy coastal morning, with fog heavy enough to dampen paper and a raucous crowd of gulls hooting from the roof of the nearby lab. The shallow pools initially appeared abandoned at low tide, but a closer look revealed dozens of tiny creatures going about their underwater business.