The slab is irregular in shape and heavily weathered, standing roughly 0.9 metres tall and carved with a three-line cross whose arms terminate in distinctive D-shaped loops, with a circle at the centre. On its right-hand face, very faint traces of an inscription survive, the kind that rewards long looking in raking light. Of whatever text was once cut there, only a single letter O remains clearly legible in the upper quarter. The rest has gone, worn away to a whisper.

The slab was not found in Galway at all. It came to light during ground-clearance works near the early Christian church on Inchbofin, a small island on Lough Ree in Co. Westmeath. Cross-slabs of this type, upright stones incised with a cross and sometimes an inscription or name, are among the most characteristic markers of early medieval Irish ecclesiastical sites, and island monasteries in particular often produced them in some number. The Inchbofin example was recorded as Slab B in an appendix to the Commissioners of Public Works annual report for the year ending March 1913, and noted by the antiquary H. S. Crawford in the same year. At some point after its discovery it was transferred to the OPW depot at Athenry, which is where it remains, a county away from the island where it spent perhaps a thousand years in the ground.