The site is modest in scale, roughly nine metres north to south and six metres east to west, and its raised profile is the main thing that marks it out from the surrounding landscape. Dozens of roughly cut stones, placed without inscription, indicate graves oriented east to west in the manner of Christian burial, yet the plot itself sits outside the main body of the church enclosure, a deliberate positioning that reflects a long and quietly sorrowful tradition.

Places of this kind are known in Irish as cillíní, and they served as informal burial grounds for unbaptised infants, stillborn children, and others considered ineligible for burial in sanctified church ground under Catholic doctrine as it was practised in Ireland for several hundred years. The theology involved the doctrine of limbo, which held that souls dying without baptism could not enter heaven, and this belief, combined with the pastoral reality of high infant mortality, produced hundreds of such sites across the country, often located at the margins of early monastic or ecclesiastical enclosures, at boundaries, on the edges of townlands, or near ancient earthworks. At Cloonkeen, the choice of the south-east quadrant of what appears to be an early ecclesiastical site suggests the ground had long been associated with the sacred, even if formally it lay at its periphery. The roughly worked stones, uncarved and anonymous, were the only markers families could leave.