Limpets have taken up residence in an almost perfectly round ‘bowl’ hollowed out of the red sandstone by time and nature. Sandeel Bay is full of such features and even larger hollows present are a reminder that large mill wheels, water troughs and other objects were one hewn out of the bare rock.
While the majority of the peninsula is limestone, a band of Devonian old red sandstone runs across the peninsula from Broomhill to Carnivan. This sandstone is made up of sand grain sized particles which because of the hardness of individual grains and the uniformity of the grain size meant that it was perfect for making mill wheels for grinding grain.