This is a fulacht fia, a type of site found in enormous numbers across Ireland, typically interpreted as an ancient outdoor cooking place where water was heated by dropping fire-cracked stones into a trough. The burnt and shattered stones, discarded repeatedly after use, gradually built up into the characteristic mound that survives today. The mound at Lackareagh measures eight metres along its NW-SE axis and four metres across, rising to a maximum height of around 0.6 to 0.7 metres at its south-west and south-east edges, with a slight opening to the north-east.

What makes the Lackareagh example quietly striking is not the mound itself but its company. Three further fulachta fia lie within a hundred metres: one roughly twelve metres to the west-north-west, another approximately seventeen metres to the west, and a fourth around a hundred metres to the east-south-east. This kind of clustering is known elsewhere in Ireland, and it raises questions that archaeologists have not fully resolved. Were these features used simultaneously by a larger group, or do they represent repeated activity at a favoured spot over many generations, each mound accumulating and being abandoned before the next was begun? The proximity to the small stream running roughly north-north-west to south-south-east is consistent with the practical demands of the fulacht fia tradition, which required a reliable water source close at hand.