On the northern edge of Quissett Harbor

After finding that arrowhead, I went to have a closer look out the path to the Knob. Not seeing anything interesting, I walked back along the shoreline on the edge of Quissett Harbor. Saw this and didn't think too much of it:

Maybe just someone having a fire by the beach. Then there was another:

And another:

It looked like there might be a secondary ring outside the first. 

By this time, maybe I was seeing things:

Anyway, the question arises: could these things be old? They are a little peculiar. In the first three, the larger rock has a kind of "eye socket" flaked out of it.

Closer to my car, here is a midden that people around here have never mentioned, so they may not know about it:

The midden is a layer of broken shells, showing white in the picture, above left of the right-hand boulder.
Back near the car, the juniper berries are a nice deep blue: