Colorful Stones on the Serpent's Back

I visited the Snake/Serpent Effigy (on a Land Trust Property in Woodbury CT) shown above for the third time just the other day. It has some interesting stones on its back (as if the head stone itself isn't interesting enough). Right on top of the alleged head:

Moving north:

And then there is the testudinate one, a mix of quartz and another type of stone, above that square piece of white quartz:

This one:

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http://wakinguponturtleisland.blogspot.com/2012/09/a-single-stone-turtle-effigy.html