The stone is not large, roughly 1.72 metres long and less than half a metre high, and it would be easy to walk past it entirely. What makes it worth stopping for is what has been carved into its flat upper face: a series of cup-and-ring marks, the prehistoric motif type in which a shallow circular depression, the cup, is surrounded by one or more concentric incised rings. This boulder carries examples with one, two, and three surrounding rings, along with four plain cupmarks and several connecting grooves, one of which runs 35 centimetres across the stone to terminate beside a cupmark at its western edge. The grooves linking some of the motifs to one another give the composition an unusual internal geometry, as though the carvings were intended to relate to each other rather than simply accumulate.

The boulder sits within the bounds of a pre-bog field system, meaning the landscape around it was once organised agricultural ground before the bog grew over it, a process that began in the Bronze Age across much of upland Ireland. Cup-and-ring rock art in Ireland is generally attributed to the later Neolithic or early Bronze Age, roughly 2500 to 1500 BC, though its precise function remains unresolved. The Iveragh Peninsula has a notable concentration of such carvings, documented in the 1996 archaeological survey of South Kerry by A. O'Sullivan and J. Sheehan. The Maghanlawaun boulder was recorded in that survey, though a later survey by Alison McQueen and Vera Rahilly noted some discrepancies, likely because moss and lichen cover obscures parts of the decorated surface and makes the motifs genuinely difficult to read at close quarters.

The site sits at about 130 metres above sea level on the eastern side of a low ridge, with open views across the Bridia valley and toward MacGillycuddy's Reeks to the north-east. A low, semi-circular stone wall curves around the rock art to the east, south, and west, with its nearest point about four metres from the boulder itself. The motifs, shallow to begin with and now weathered further into the sandstone, are best seen in raking light, when the angle of the sun picks out the relief that direct overhead light tends to flatten entirely.