Archaeologists involved in a recent excavation on the site of Nevern Castle in the Pembrokeshire Coast National Park believe the markings on the slates, dating back more than 800 years, indicate some ritualistic methods of warding off evil.
Archaeologists said the scratched markings are interesting for several reasons, but mainly because of the rarity.
“Scratched images from the medieval world are rare, and we can confidently date these to the period 1170-1190 when the stone phase of Nevern Castle was built,” added Dr Caple.
Archaeologists uncover slate at Nevern Castle 'that kept evil spirits as bay'. --WalesOnline