It dates from the 13th or 14th century, measures just over two and a half metres in length, and was carved from grey fossiliferous limestone, a stone dense with the compressed remains of ancient marine creatures. What makes it quietly arresting is the precision of its making: smooth on both interior and exterior surfaces, shoulders curved to accommodate a human form, a penannular head recess where a pillow was raised some five centimetres above the floor, and a slight taper along the outer sides towards the foot. Two small cylindrical soakage holes, drilled to drain away fluids, are a reminder that this was a functional object before it became a historical one.

For much of its known history, the sarcophagus sat outside. By the time the historian Canon William Carrigan documented it around 1905, it had already been placed against the external face of the south wall of the nave, an arrangement that had presumably stood for some time before he recorded it. Whether it began its life inside the church and was later moved out, or was always positioned there as a kind of yard monument, is not recorded. It remained in that outdoor position for well over a century until 2016, when it was finally brought inside the nave, sheltered at last from the Kilkenny weather.