It measures just 20 centimetres tall and little more than 19 centimetres wide, a triangular sliver of carved rock that arrived in Dublin in 1971 from one of the most remote early Christian sites in Ireland. Its present address, a museum in the south of the capital, could hardly be further in spirit from where it began.

The fragment comes from Inishmurray, an island off the coast of Co. Sligo that once supported a monastic settlement of considerable importance. It was removed in 1971, most likely from the cashel, the roughly circular stone enclosure that defines the core of the island's early medieval monastery, and assigned the museum catalogue number 1971:1114. What survives is the lower portion of a cross-slab, a stone carved with a cross motif, a form commonly associated with early Irish Christian sites and used for everything from grave markers to devotional objects. The carving itself, documented in a detailed archaeological survey of Inishmurray carried out between 1997 and 1999 and published by Jerry O'Sullivan and Tomás Ó Carragáin in 2008, is quietly sophisticated. Two parallel ridges in false relief, meaning they appear raised without being fully cut free from the background, descend and converge to a point. Below that, a V-shaped trough opens outward, and each arm of the V resolves into a two-turn spiral, mirrored on either side. The overall effect is controlled and precise, even in so small a piece.

For anyone wishing to see the fragment, it is held by the National Museum of Ireland, whose archaeology collections are based at Kildare Street in Dublin city centre. Whether any particular piece from the reserve collection is on open display at a given time is worth checking in advance. The object's original context on Inishmurray, recorded separately under its own site number, remains on the island, which is uninhabited and accessible only by boat from the Sligo coast. The 2008 volume by O'Sullivan and Ó Carragáin remains the most thorough guide to what survives there, for anyone wanting to understand where this small carved stone once belonged.