Amphipods? Most people didn’t know that these tiny shrimplike creatures existed until Friends of the Capital Crescent Trail began to hunt for the 5- to 15-millimeter crustaceans along the proposed route of the Purple Line. One species of amphipod, called the Hay’s Spring amphipod, is on the federal list of endangered species and is believed to exist in the Rock Creek area. An American University scientist hired by the group and paid for by the Town of Chevy Chase wasn’t able to find any Hay’s Spring amphipods during his first search last spring, so hopes now rest on testing water and sediment along the trail for amphipod DNA. If the tests come back positive, a federal lawsuit the group filed alleging harm to amphipods because of the Purple Line project may have some merit.