It measures roughly sixteen metres north to south and eight metres east to west, and its composition, heat-shattered stones mixed through charcoal-enriched soil, is the only real clue that something deliberate happened here a very long time ago. A forestry drain has cut through it, which has not helped its legibility on the ground.

What survives is what archaeologists call a burnt mound, one of the most common yet least-understood monument types in the Irish landscape. The working theory, broadly accepted though not universally settled, is that these accumulations represent the waste from repeated episodes of heating stones in fire and then plunging them into water-filled troughs, perhaps for cooking, bathing, or industrial processes such as working hides. The stones fracture and become useless, so they are discarded nearby, building up over time into the characteristic low spreads that survive today. Thousands of them are known across Ireland, most dating to the Bronze Age, and they tend to cluster near water sources. The Ballydaheen example fits the general pattern well enough, though its precise date and function remain unrecorded.