When I first saw it, I thought it was a piece of paper plastered onto a wet rock. Then maybe it was part of a fish. But when I got closer, I saw it was a fossil of a shell, encased in rock. Part of the shell had worn away, but the darker grooves of the shell remained, looking almost like shell shadows in the photograph. The rock was pancake flat, encircled by a little moat of sea water.
We spent 127 minutes on the beach this morning at low tide. How long has this shell spent embedded in rock?