The larger of the two is kidney-shaped, roughly twenty metres from east to west and over twelve metres across, rising to about one and a half metres in height. It is composed of burnt limestone, the accumulated debris of repeated heating and cooling that has left the stone cracked and discoloured. Between the two mounds there is a shallow depression, possibly once an opening facing roughly south-south-west.

The site is a fulacht fia, a type of monument found in considerable numbers across Ireland, most commonly dating to the Bronze Age. The usual interpretation is that these were outdoor cooking places: stones were heated in a fire and then dropped into a water-filled trough to bring it rapidly to the boil. Over time, the thermally fractured, unusable stones were raked out and piled to the side, building up exactly the kind of curved or horseshoe-shaped mound visible here. The preference for low-lying, wet ground makes practical sense, since such locations provided a reliable water source, though the specific trough at Kilcloghans has not been described in available records. The eastern mound at this site is notably well-preserved; immediately to its west, a smaller rectangular mound of similar burnt stone suggests either a secondary phase of activity or a distinct but associated feature.