On one face, carved in a single continuous groove, is a Latin cross, its arms ending in slightly widened, expanded terminals and enclosed within a circle, with low ridges separating the head and base from the arms. Nobody now knows exactly where on the island it originally stood. That uncertainty is part of what makes it quietly compelling: a precisely observed object whose original context has been lost, moved indoors for safe-keeping along with two companion cross-slabs, their former positions unrecorded.

Illauntannig is the largest of the Magharee Islands, a small archipelago lying off the northern tip of the peninsula that divides Brandon Bay from Tralee Bay in County Kerry. The island holds one of the more complete Early Christian monastic settlements surviving in Ireland. Within a cashel wall, a thick enclosing boundary of dry-laid stone typical of early Irish ecclesiastical sites, there are two small oratories, three beehive huts, a souterrain (an underground stone-lined passage, often used for storage or refuge), a wall-chamber, three leachts (low stone platforms associated with prayer and commemoration), a burial ground, and a standing stone cross. Beyond the cross-slabs now housed in the oratory, excavations or surveys of the enclosure have also turned up a bullaun stone, a hand-bell, and fragments of five quern-stones. A second bullaun stone, a basin-shaped hollow ground into rock and used in early Christian practice, sits roughly a hundred metres to the south at the island's edge. Across the water on Reennafardarrig, a hut-site, old field walls, and a reputed cross-inscribed boulder may belong to the same monastic network. The settlement was documented by J. Cuppage in a 1986 archaeological survey of the Dingle Peninsula.

The island is accessible by boat from the Maharees peninsula, though crossings depend on sea conditions and are not formally scheduled. The oratory where the cross-slabs are now kept is the natural focus of any visit, and the carved stone described here, compact and rounded, rewards close attention: the geometry of its incised cross is deliberate and assured, the work of someone who knew exactly what they were making, even if the stone's original place in the settlement's life remains unknown.