That structure, just 1.2 metres wide and less than a metre in confirmed length, was so slight that archaeologists have struggled to agree on what, exactly, it was for. It is not the kind of monument that announces itself.

Four seasons of excavation between 1992 and 1995 uncovered about 70 per cent of Illaunloughan, revealing a layered sequence of sacred building that stretched back well into the early medieval period. An oratory is a small private chapel or prayer room, and the island eventually produced evidence of three successive structures built in roughly the same spot. The earliest was a sod-built oratory, a building whose walls were cut from turf rather than stone, a technique common in the Irish early church when permanent materials were scarce or impractical. The second, the anomalous one, replaced it: two parallel trenches packed with rectangular sandstones, possibly once holding sod walls no higher than 1.5 metres, with what appears to have been a light thatched roof resting directly on them. A radiocarbon date of 640 to 790 AD was recovered from a layer above the clay floor of the later drystone oratory that followed it. Researchers Marshall and Walsh suggested the tiny intermediate structure may have served a transitional purpose during building works, perhaps storing relics and liturgical equipment, including Gospel books, while a gable shrine was under construction nearby. What makes the sequence particularly striking is that the builders of the final drystone oratory appear to have deliberately incorporated elements of the earlier structures into their own walls, leaving upright stones of the small building untouched beneath the new masonry, seemingly to preserve a physical and spiritual continuity between them. The name of the island itself remains uncertain; Lochán may refer to a saint associated with the site, a possibility supported by two figures of that name appearing in the Martyrology of Oengus, compiled around AD 800, or it may simply mean the island of the chaff. There is no surviving historical documentation to settle the question either way.