Only partial ruins remain of the dormitory undercroft of Christ Church Priory. To find them walk via the main cloister towards the water tower.  Turn left before the water tower and follow the images above – the example of Thanet Sandstone can  be seen in the wall behind the seats shown above. The third image (right) shows piddocks (marine bivalves) in Thanet Sandstone "holes".  We conclude that the stone was collected by the medieval labourer from the foreshore.