In slow moving portion of the brook after crossing, from sandy substrate with small rocks
another case of freshwater mussel washing up on marine beach...
mysterious. resembles a freshwater mussel, yet found on a marine beach. due to the amount of acorns and so forth (and there being a huge Marsh close by), could have been flushed out of a freshwater river into the ocean to wash up here?
My phone wouldn't focus on the right thing before it flew off, but at least it's still identifiable.