It was only when one of the island's Later Medieval shelters was examined more closely that the slab revealed itself for what it actually was: an early cross-slab, repurposed by later builders who either did not recognise it or did not mind reusing it as ordinary construction material. That kind of casual recycling is surprisingly common on early Christian sites, but it still produces a small jolt of incongruity when you consider what the object was originally made to be.

The slab is rectangular, cut from slate, and measures just over a metre tall by roughly half a metre wide. Its upper left corner has broken away at some point, but the carving it bears remains legible: a grooved, linear Latin cross with rounded terminal expansions, meaning that each arm of the cross ends in a circular or lobe-like flourish rather than a plain straight cut. This style of incised cross appears across early Christian Ireland and is associated broadly with the early medieval period, when small monastic communities on islands such as this one marked burials, boundaries, or places of prayer with relatively simple but carefully worked stones. The Iveragh Peninsula in south Kerry preserves a remarkable concentration of such early ecclesiastical remains, and Church Island itself takes its name from the religious settlement that once occupied it.