Found in the rubble of a collapsed drystone cell on High Island, a remote and exposed outcrop off the Connemara coast in County Galway, it is made from garnet mica-schist, a metamorphic rock with a faintly glittering quality that sets it apart from the rougher building stone around it.

The slab tapers slightly and was recorded by Fisher in 2014 during work connected to the early medieval monastic remains on the island. It emerged from the debris of what is designated Cell B, one of the clochans, or beehive-shaped stone huts, that stood to the east of the island's church. Both faces are carved with expansional crosses, a form in which the arms widen towards their ends, here finishing in D-shaped terminals. On the more complete face, the lower terminal may originally have enclosed a triquetra, the three-cornered interlaced knot associated with early Christian art in Ireland. Bosses, small raised roundels used as decorative accents in early medieval stonework, appear in the upper quadrants, and at the top corners pairs of bosses are connected by C-scrolls or peltae, leaf-shaped forms borrowed ultimately from classical ornament. The second face is less well preserved, with only the left and upper terminals still clearly legible, and the central area of the cross there takes a lozenge rather than a circular form. Taken together, the two faces represent a notably sophisticated programme of carving for an object of such modest dimensions.

The slab is no longer in the open. It is currently held in the Office of Public Works depot on the island, removed from the elements that have already cost it some of its detail. High Island itself is privately owned and landing is subject to sea conditions on a coast that offers little shelter, so access to any of the monastic complex there is far from straightforward.