What makes it quietly arresting is not just its age but a detail embedded in its Latin inscription: Maurice O'Kearny and his wife Ellen Purcell commissioned the slab together, yet Maurice died on 22 December of the very same year it was made. The stone was ordered in life and used almost immediately.

The slab is a tapered rectangle of limestone, two metres long and narrowing from roughly 89 centimetres at the head end to 78 centimetres at the foot, a standard enough form for the period but well preserved given its nearly four centuries on an abbey floor. Its surface carries a seven-armed cross, an unusual variation on the more familiar form, with fleur-de-lis terminals at the ends of each arm and a cross-shaft rising from a pyramidal base. The inscription runs around all four edges in Latin: "Hic jacet Mauritius OKearny et Elena Purcelleius uxor qui me fieri fecerunt", which translates as here lies Maurice O'Kearny and his wife Ellen Purcell who had this made. The lettering is worn in places but legible enough to reconstruct the full text, including the date of Maurice's death: 22 December 1643. Whether Ellen survived him by days, months, or years, the slab does not say. Holycross Abbey itself is a Cistercian foundation on the River Suir, long associated with a relic of the True Cross, and remained a place of some spiritual significance even through the upheavals of the seventeenth century, which makes the commissioning of such a carefully decorated stone in that year all the more striking.