The stones had been left by mourners, one by one, over generations. The structure they surrounded is a leacht, a type of ritual or memorial altar found in Irish ecclesiastical and burial contexts, typically a low cairn or built setting of stones used as a focus for prayer and devotion at a graveside.

The excavation, carried out in 2003 ahead of the road project and later published by Nolan in 2008, revealed the leacht sitting in the western half of a burial ground at Tonybaun. It was roughly square, measuring 1.8 metres by 1.8 metres, and survived to only two courses of stonework in height. Two fragments of quern stones, the flat grinding stones used for milling grain, had been worked into its walling, a detail that hints at the kind of practical reuse common in vernacular construction. Radiocarbon dating placed the establishment of the burial ground in the late fifteenth century, and it remained in use into the early twentieth century. Its final phase was as a cillín, a children's burial ground, the informal and often unrecorded burial places used for unbaptised infants and others excluded from consecrated ground. The leacht itself belongs to the earlier phases of the site, though its precise construction date remains uncertain.

What makes the Tonybaun leacht quietly striking is the accumulation of those votive cobbles. The practice of placing a stone at a leacht or at a graveside, often a stone carried from a distance or picked up from a riverbed, is documented across Ireland, but to find over 700 gathered in one spot, preserved beneath the soil until a road scheme disturbed the ground, gives some material weight to what is otherwise an intangible act of remembrance. Each cobble represents a visit, a grief, a habit of devotion maintained across roughly four centuries.