And in my yard was and is a large zigzag row of boulders of similar shape and size:
I’ve lost the pictures of the excavation in a computer crash, but I removed leaves and periwinkle to find two feet for this turtle (I added another headstone for the picture).
It has toes carved into each stone that is shaped to fit into the carapace.
Eventually only stone was left. These seem to be of a certain pattern, although only about a third of the size of the others.