This one surfaced because someone was digging gravel. In 1953, quarrying operations on a gravel ridge near the confluence of the Blackwater and Derreendarragh rivers in County Kerry broke open a souterrain, an underground stone-built passage roofed with slabs, of the kind used in early medieval Ireland for storage or refuge. The souterrain itself was destroyed in the process, but standing loose within it was a slab of shaly sandstone, 1.45 metres long and smoothed along its inscribed face and side, carrying one of the older scripts of the Irish language cut in well-spaced, narrow scores.

Ogham is an early Irish alphabet, typically carved along the edge or angle of a stone, in which groups of strokes represent letters. The inscription on this stone runs up the dexter angle, meaning the right-hand edge as you face it, and reads BRANADDOVMA MAQI QOLI MUCOI DOVIV, with the final character uncertain, possibly an N or S. The scholar Damian McManus, writing in 1997, proposed a slightly different reading: BRANADDOV MA[QI] MAQIQOLI MUCOI DOVI[NIAS], reconstructing letters that had been lost when the upper end of the stone was broken off, apparently long before it was found. The formula itself is familiar from many early Irish ogham inscriptions, recording a personal name followed by a lineage, using the archaic Irish word MAQI for "son of" and MUCOI to indicate a tribal or kin group. The stone's lower end is roughly tapered, suggesting it was once intended to stand upright, possibly as a grave marker or boundary stone, before it ended up, by whatever route, inside a subterranean passage that no Ordnance Survey map had ever recorded.

The stone is now held at Cork Public Museum, having travelled some distance from the Kerry riverbank where it spent centuries underground.