It measures somewhere between six and eight metres across and barely reaches thirty to forty centimetres in height. Shallow furrow-like grooves run across its surface on a north-south axis, and beneath a layer of dark peaty soil the mound is composed of shattered sandstone. Nothing about it announces itself, yet this modest hump in the ground is the physical residue of prehistoric activity that was once entirely practical and probably communal.

The site belongs to a category known as fulachtaí fia, a term for burnt mounds that appear in considerable numbers across the Irish landscape, typically beside streams or in waterlogged ground. The general understanding is that they accumulated through repeated heating of stones, which were dropped into water-filled troughs to boil the water, then discarded once they cracked and shattered from thermal stress. Over time, the broken, fire-reddened stones piled up into the low mounds we see today. Debate continues about whether these sites were primarily used for cooking, bathing, textile processing, or some combination of purposes, but their association with running water and wet ground is consistent. What makes the Killeen example particularly notable is its setting within a linear cluster of such mounds strung along the course of the Fiddaunglass stream, with at least one other burnt mound lying just twenty metres to the south-west. The repeated use of this specific waterway suggests the location held some sustained, practical significance over a long period.