The cairn sits on a gently south-facing slope of grassed-over karst limestone in the Burren, that famously bare and fissured landscape of County Clare, set within what appears to be a large field system used across multiple periods of history. The mound itself is modest, measuring roughly 7.2 metres across at the base east to west and rising only 0.7 to 0.9 metres in height, with a noticeably flat top about 4.9 metres wide. Composed of stones and slabs, some of which still stand or lean at angles, it has the look of something interrupted rather than finished.

The protruding slab at the summit, oriented NW-SE and measuring a metre in length, is not simply a stray piece of limestone. Smaller stones have been placed against its south-western face, forming a small cavity. The antiquarian T. J. Westropp, writing in 1915, identified this as the remains of a slab cist, a type of simple stone-lined burial box typically associated with prehistoric interments. The cairn was already being mapped by the time the Ordnance Survey produced its 25-inch plan in 1897, where it was marked and labelled as 'Carn', and it appeared again on the 1920 edition of the six-inch map. About 55 metres to the west-northwest stands a cashel, a stone-walled enclosure of the kind common to early medieval Ireland, a reminder that the ground around Ballyganner was used and reused across a very long span of time.