The rectangular pillar, standing 1.32 metres high and just 10 centimetres thick, carries on its western face a ringed Latin cross with open-ended terminals, its upper arm stepped and finishing in spirals. Above the cross sits a double circle bisected by two vertical parallel lines, and it is through this circle that the hole is pierced. The entire composition is contained within a single incised groove running around the slab's edges, giving the carvings a deliberate, unified quality that suggests careful planning rather than accumulation over time.

The scholar R.A.S. Macalister, writing in 1922, was the first to propose that the pillar functioned as a sundial. On this reading, a stick inserted into the hole would have served as a gnomon, the part of a sundial that casts the shadow, and midday would have been indicated when that shadow fell along the vertical lines running through the circle's diameter. It is a plausible interpretation: monastic communities had a practical need to regulate the hours of prayer, and the slab stands only about five metres east of Teampall Chiaráin, one of the early ecclesiastical structures on the island. The cross carving, with its ringed form and spiralling terminals, is consistent with early medieval Irish stonework, placing the object within a tradition of religious art that also had to serve the daily rhythms of communal life.

The slab is set close to Teampall Chiaráin, so anyone visiting the church will find it nearby. The western face, where all the carving is concentrated, catches the afternoon light, which makes the incised lines easier to read. The small pierced hole above the bisected circle is easy to overlook at first glance, but once noticed it reframes everything else on the stone.