It began its known history on a remote island off the Sligo coast, resting on an altar inside one of the most complete early medieval monastic enclosures in Ireland, and it carries on its surfaces a quiet puzzle that scholars have yet to fully resolve.

Inishmurray, a low-lying island in the Atlantic some five kilometres off the Sligo shore, was home to an early Christian monastic settlement associated with Saint Molaise, and its stone church known as Teach Molaise, meaning the house of Molaise, was among the structures that survived largely intact into the modern era. The antiquarian W. F. Wakeman recorded this particular fragment in 1893, noting its position on the altar within that church. The slab fragment measures 0.285 metres high, 0.16 metres wide, and just over five centimetres thick. On one face, incised into the stone using a false relief technique, in which the surrounding surface is cut away to leave the design slightly raised, is what appears to be the base of a cross motif: a circle with a small central boss, a curving strand that may once have extended upward as a cross shaft, and two parallel lines running axially from the base. On the opposite face, two letterforms are almost entirely worn away; the National Museum of Ireland's register tentatively reads them as either 'D' or 'O', and 'R'. A survey carried out between 1997 and 1999, published by Jerry O'Sullivan and Tomás Ó Carragáin in 2008, raised the possibility that this fragment and another from the same island site may originally have formed part of the same cross-slab.

The fragment was removed from Inishmurray to the National Museum of Ireland in 1971, where it is held under register number 1971:1115. The museum's collections in Dublin are freely accessible, though individual items from the archaeological holdings are not always on public display and an enquiry to the collections staff may be necessary before a visit. The island itself, now uninhabited since its population was evacuated in 1948, can be reached by boat from the Sligo coast during summer months, and the monastic enclosure remains visible on the ground, though the altar stone that once held this fragment is no longer complete.