Loch of Skaill Niche

The OS position is imprecise because the site lies on a very plain stretch of the road alongside the Loch of Skaill. It seems strange that in this general area there is nothing noted apart from a quarry. I have called this a natural rock formation (despite its regularity) just to be on the safe side. But it does stand out as possibly man-made, perhaps the corner of something that mostly still is hidden by the road overhang on this section of road. Could it be a step in a wall? To me what one can see presents the appearance of a triangular niche for some unknown purpose of its own.