Look more carefully and a shallow trench cuts across it on a roughly east-west axis, giving the impression of two separate humps sitting side by side. That trench is the clue that something far older is going on here. This is a fulacht fia, one of the most common prehistoric monument types in Ireland, and one whose purpose still generates quiet debate among archaeologists. The term refers to a burnt mound, typically Bronze Age in date, thought to represent an outdoor cooking or processing site where water was boiled by dropping fire-heated stones into a trough. The shattered, heat-fractured stones accumulate over time into a distinctive horseshoe or kidney-shaped mound, which is precisely what the Ballynacourty example appears to have been originally before later disturbance reshaped it.

The mound itself measures roughly eleven metres on its longer axis and rises to about 0.8 metres, modest dimensions but consistent with the type. Its kidney shape, opening toward the northeast, is the classic form, and the trench cutting across it is likely a later intrusion rather than an original feature. What makes the site quietly remarkable is its company. The broad, shallow valley in which it sits contains at least three other fulachta fia nearby, suggesting this low-lying corridor of land was used repeatedly, perhaps across generations, for whatever communal activity these monuments represent. That clustering is not unusual; fulachta fia tend to appear near water sources, and valleys like this one would have offered both ready access to streams and relatively sheltered ground.