The mound measures roughly ten metres east to west and nine metres north to south, rising to a modest height of about sixty centimetres. Stone-filled and worn smooth by time, it is the kind of feature that reads as a natural undulation until you look more closely.

Burnt mounds are among the most widespread prehistoric monument types in Ireland, and among the least understood in terms of precise function. The working theory is that they represent the accumulated debris of a process involving fire-heated stones, which were dropped into a water-filled trough to bring the water rapidly to the boil. The trough at Lissardboola, a roughly three-metre-square depression opening to the north, is still faintly visible, though considerably eroded. Once the stones cracked and became unusable from repeated heating, they were discarded, building up over time into the characteristic mound. The black, burnt appearance of the surrounding soil is consistent with exactly this kind of sustained, repeated use. What the heated water was actually for remains debated: cooking, bathing, textile processing, and ritual use have all been proposed. The site sits beside a second burnt mound in an adjoining field, suggesting this corner of the Lee Valley saw repeated or prolonged activity of this kind. The area was surveyed in the mid-1990s as part of a broader examination of the Lee Valley.