It holds the distinction of being the first ogham stone ever recorded in Ireland, ogham being the early medieval script in which letters are represented by a series of notches and scores cut along the edge of a stone, most commonly used for commemorative inscriptions. The stone carries both a plain Latin cross on its upper surface and an ogham inscription along one edge of the same face, and the relationship between the two is itself a small puzzle: the second L-score in the inscription appears to have been deliberately shortened to avoid cutting across the arm of the cross, which suggests the ogham was carved after the cross, though perhaps not long after.

The earliest known account of the stone appears in a manuscript note by the Welsh antiquary Edward Lhwyd, dating to around 1702 to 1707, when it stood upright in a field near the strand. By the early nineteenth century it had already fallen onto the shore, where it was periodically washed by the high tide. In 1849 it was briefly removed to Chute Hall before being returned. The ogham inscription reads BRUSCCOS MAQQI CAL(I)AC(I), a formula typical of early Irish memorial stones, broadly meaning something like "[name], son of [name]". R. A. S. Macalister, the twentieth-century epigrapher, argued the inscription was longer and continued around another edge, but later examination found no convincing evidence for this, and even the marks he took as the start of an additional word are considered doubtful. The stone is known locally as Cloch an tSagairt, the Priest's Stone, while the place-name Leac Shiobhán na nGeimhleach that appears on Ordnance Survey maps actually belongs, according to the folklorist An Seabhac writing in 1939, to a separate rock further out on the strand. The surrounding area carries its own quiet accumulation of history: a tradition of an old church at the strand was noted as early as 1838, and a graveyard a few metres inland was identified by a later researcher, with a single grave exposed in an eroding bank and others reportedly turned up during ploughing.