It is not much to look at on paper, but that modesty is precisely the point. A fulacht fia, to give the type its Irish name, is one of the most common prehistoric monument classes in Ireland, yet the majority were never formally investigated. This one only came to light because a road was being built through it.

The site at Ballycummin was identified during archaeological monitoring carried out in connection with the N20/N21 Limerick Bypass, and excavated by Ciara MacManus under licence number 99E093 in 1999. A fulacht fia typically consists of a trough, usually timber-lined or cut into the ground, which was filled with water and heated by dropping fire-cracked stones into it; the spent stones were then thrown aside, gradually building up the characteristic low, horseshoe-shaped mound that marks these sites across the Irish landscape. At Ballycummin, the main trough was a subrectangular pit measuring two metres long, 1.2 metres wide, and 0.4 metres deep, oriented east to west. Two further pits lay nearby, a smaller linear one to the east and a subcircular pit about 1.6 metres to the south-east. The trough itself had been filled with charcoal-rich, blackened material containing large quantities of burnt stone, sealed beneath a layer of redeposited subsoil. The original trough had sat on a small ridge surrounded by marshy ground, with the slope falling away to the west; a spread of mound material roughly 0.13 metres thick had accumulated down that slope, the physical residue of repeated use.

Only partial remains were recovered. A plough furrow to the east of the trough and a French drain, a type of rubble-filled drainage channel, to the west together account for the loss of much of the site, casualties of agricultural activity at some point after the monument fell out of use. The location is not accessible as a visitor destination; it was excavated in advance of road construction and no surface trace remains. Its value lies less in what can be seen than in what the excavation record preserves, a precise, if incomplete, picture of how one community in prehistoric Limerick organised the mundane but essential work of heating water on a marshy ridge on the edge of what would eventually become a city.