According to Canmore: "A prostrate monolith measuring 1.8m in length by 0.6m in width and 0.4m in thickness". It was once thought to have been part of a circle but may have been actually part of a cairn. Victorian sources give its local names as 'The Catholic Chapel' and 'The Papish Kirk'. Sounds rather scathing! I've read that pockets of Catholicism remained in Aberdeenshire after the Reformation - but maybe not round here, then. Doubtless someone with more knowledge of Scottish religious and social history could interpret further.