The feature at Dunbrody measures roughly fifteen metres along its longer axis and ten metres across, with a distinctive opening facing north-east. It only becomes fully visible when the land is turned over, which means that for much of the year it lies just beneath the surface, unremarked.

What is visible here is a burnt mound, a type of site found widely across Ireland and Britain, generally dating to the Bronze Age, though some examples extend into the Iron Age. The classic interpretation is that burnt mounds were the debris left behind by a particular method of heating water: stones were fired in a hearth, then dropped into a trough or pit of water to bring it rapidly to a boil. Repeated cycles of heating and quenching shatter the stones, and over time the cracked, blackened fragments accumulate into the characteristic mound of dark spoil. What the hot water was actually used for remains a matter of debate among archaeologists, with cooking, bathing, and craft processes such as working leather all proposed as possibilities. The site at Dunbrody sits towards the bottom of a south-west-facing slope, on the eastern side of a valley running roughly south-east to north-west. The stream that would likely have supplied water for such activity lies about a hundred and fifty metres to the south-west, close enough to be practical, far enough to suggest the mound accumulated at a slight remove from the water source itself.