This remarkable feature was once a sea stack but the sea level is now lower than it was and so it is high and dry. The former sea cliffs are behind.
What makes it totally remarkable is the nature of its composition. It is a type of conglomerate that seems to include whole slates. It doesn't look natural! This rock isn't like any of the others round here. No one knows exactly how to age it. It could be Old Red Sandstone or it could be Permian - quite a difference of over 150 million years and opposite sides of the Equator!