It is a fulacht fia, a type of prehistoric cooking or processing site found across Ireland, typically identified by a distinctive spread of fire-cracked stone and charcoal-rich soil left behind by repeated heating of water in a trough or pit. This particular example measures roughly eight metres east to west and just under eight metres north to south, rising to a height of about one and a half metres, with the open end of the horseshoe facing north.

What gives the site an unexpected layer of complexity is the local tradition attached to it. According to that tradition, four bishops were buried here, and each burial was marked by the planting of a large beech tree flanking the mound. Three of those trees are still standing, positioned to the northwest, northeast, and southeast of the mound. The pairing of a Bronze Age monument with early medieval ecclesiastical memory is not unusual in Ireland, where prehistoric features were often absorbed into later Christian landscapes and given new meaning, but the specificity here, four bishops, four trees, three survivors, gives the place a quietly odd texture. Whether the burial tradition has any historical foundation or represents a folk explanation for the mound's unusual prominence in a cathedral demesne is not recorded.