Roughly rectangular, tapering slightly toward the top, it measures just 0.36 metres across and protrudes only about 0.4 metres above the ground, with the rest of its length buried beneath the surface. Look closely, though, and the face of the slab reveals something precise and deliberate: five incised lines radiating outward from a small circular hole, fanning across the stone like the spokes of a half-wheel, their ends finished with a delicate semicircular groove that gives each one a three-pronged tip. This is a medieval sundial, a time-keeping instrument carved into portable stone, and it has been sitting in this ground for the better part of a thousand years.

The circular perforation near the top of the slab is the gnomon hole, designed to hold a horizontal rod, of wood or metal, whose shadow would fall across the incised rays below. Those five lines correspond to the canonical hours, the prescribed divisions of the day by which monks organised their lives around communal prayer. The central vertical line marks noon; the horizontal lines to either side mark the outer limits of the dial; and the two diagonal lines divide the intervening space into the remaining canonical subdivisions. An incised arc curves from one edge of the slab to the other, defining the base of the dial and catching the shadow at its furthest reach. This type of instrument, sometimes called a mass dial or scratch dial, was a practical necessity at Early Medieval monastic sites, where the rhythm of prayer depended on being able to read the time from the sun. The distinctive semicircular finishing at the end of each ray is a feature shared by several other Irish examples, and the closest parallel identified is the sundial at Monasterboice in Co. Louth, a site associated with one of the most celebrated early Christian monasteries in Ireland. That two such similar objects survive at different ends of the country suggests the feature belonged to a recognised carving tradition rather than the invention of a single craftsman.