This is the tail end of a snapping turtle (I think it was a snapper).  I came across her while walking to work. I was very surprised to see a turtle this big in Boston. While you can't tell from this shot, she's about 10 inches wide and 14-16 inches long. I think she may have been laying eggs as she was partially in a hole only a few feet from a river. 

I find the shapes and textures of her shell, tail and legs, just amazing...so prehistoric looking.  I would have liked to have touched the tail, but I decided I wanted to keep my fingers!