It is marked on Ordnance Survey maps simply as "Gallaun", a term used in Irish for a standing stone, and it carries along its south-eastern angle an inscription in ogham, one of the earliest writing systems used in Ireland. Ogham script works by a series of notches and strokes cut along the edge of a stone, typically recording a personal name and patronymic in an early form of Irish. This particular stone, standing up to 2.4 metres tall and measuring roughly 0.77 by 0.45 metres at its base, is no small monument; it leans slightly to the north-east and is aligned roughly north-north-west to south-south-east.

Reading the inscription is not straightforward. The surface of the stone is heavily weathered and uneven, and scholars have had to work carefully around gaps and ambiguities. R. A. S. Macalister, whose revised reading was published in 1945, interpreted the text as something close to ERRLONNA MAQI RUTENI, repeated twice with slight variation, suggesting a name and a father's name in the genitive form typical of ogham inscriptions. Several individual characters remain doubtful: the first stroke of the L is unclear, only two notches of one I are legible, and the final E and I of the patronymic are uncertain. The formula MAQI, meaning "son of", is a standard construction on these stones and one of the more reliably read elements here. A second ogham stone stands around 400 metres to the north-east, within the Kildreenagh ecclesiastical site, making this corner of Valentia Island an unusually concentrated area of early medieval epigraphic activity.