This is a fulacht fia, a type of site found in enormous numbers across Ireland, typically dating to the Bronze Age. The defining feature is the mound itself, formed from thousands of fire-cracked stones discarded after repeated heating. The accepted explanation, though debated among archaeologists, is that stones were heated in a fire, then dropped into a water-filled trough to bring it to the boil, possibly for cooking, bathing, or industrial processes such as working hides.

The mound at Bunanumera measures thirteen metres in length and twelve metres wide, rising to a height of just over a metre. Its opening faces south, spanning three and a half metres, giving it the characteristic horseshoe outline. Close by lies a dried-up well, which is a detail worth pausing on. Fulachta fiadh are almost always found near a water source, since the whole process depended on a reliable supply. The well here has long since dried out, but its presence confirms the logic of the site's location on a west-southwest-facing slope, where water would once have gathered or surfaced naturally.