The island, Illaunakilla, is one of a cluster collectively known as the Greenane Islands, and somewhere on it lies what the Ordnance Survey Name Books once described as an old burial ground "not used these three hundred years". That phrase, recorded in the nineteenth century, places the last interment somewhere around the 1500s, though whether the ground was ever formally consecrated or simply used by necessity is no longer known. These small, unofficial burial grounds are not uncommon across Ireland; they were often set aside for unbaptised infants, who under Catholic practice were excluded from consecrated churchyard soil. The isolation of an island, in that context, was not always accidental.

The islands themselves carry further traces of early religious life. A second island, Carraig a tSagairt, lying to the north-east of Illaunakilla, was noted as a place where priests celebrated Mass during the fifteenth and sixteenth centuries, a period when practising Catholic clergy in Ireland operated under sustained legal and social pressure. The name translates roughly as "the priest's rock", which speaks plainly enough to its function. Together, the two islands suggest a cluster of clandestine or marginal religious practice, conducted at a remove from the mainland and largely outside official oversight. What physical remains, if any, survive on either island is unclear; it was not possible to visit Illaunakilla when the site was being researched, and knowledge of the burial ground has not persisted in local memory.