It measures only about five metres across and stands no more than thirty centimetres above the ground. In itself that might seem unremarkable, but the 1903 Ordnance Survey maps, both the six-inch and twenty-five-inch editions, record a far larger irregularly shaped mound on the same spot, with dimensions of roughly thirty-eight metres northeast to southwest and around twenty metres northwest to southeast. Whatever this feature once was, only a small, grass-covered remnant now remains, with no definable edges or structure visible.

A cairn, in the Irish archaeological context, is typically a mound of heaped stones, often raised over a burial and frequently associated with prehistoric activity on upland terrain. Knockanglass fits that broader landscape pattern well enough, sitting in open upland country with wide views in every direction. The surrounding area has changed considerably over time. Field boundaries have been reorganised, and a laneway that once ran from this spot down to a coal pit has entirely disappeared, taking with it whatever sense of working continuity this corner of the hills once had. The coal pit itself points to a more recent industrial past layered beneath the much older question of the mound.