Unidentified Acadia Subject #2

Found above the high-tide line on the granite coast of Acadia National Park, this strange structure has become something of an ongoing mystery. Hard, translucent, porous, and firmly attached to the rock, it remained unchanged when I returned six weeks later. Despite photographing it from nearly every angle—and spending far too much time trying to identify it—I still don't know what it is. Acadia National Park - Maine