A rath, to give the short version, is a roughly circular earthwork enclosure, typically of early medieval Irish origin, built as a farmstead and often surrounded by an earthen bank and ditch. That such enclosures were later repurposed as burial grounds for unbaptised children is not unique to Mayo; it happened across Ireland, the old earthworks carrying enough of an in-between quality, neither fully sacred nor fully secular, to suit burials that the Church would not sanction in consecrated ground.

At Ballyheeragh, the evidence is concentrated towards the east and south-east of the rath interior, where low, uninscribed stone grave-markers sit in a dense arrangement. Some are laid out in rough north-south or north-east to south-west rows; others cluster into roughly square plots, the largest measuring around seven metres across. These small squares, outlined in stone, suggest something more deliberate than scattered individual burials, perhaps families or neighbours grouping their losses together. The western half of the rath is quieter in terms of visible markers, though several grass-covered bumps in the ground may yet indicate graves beneath the surface. None of the stones carry inscriptions. The children buried here were, by the logic of the time, outside the reach of formal commemoration, and the markers reflect that: present, but anonymous.