Fulachta fiadh, the plural of fulacht fia, are among the most common prehistoric monument types in Ireland, low horseshoe-shaped mounds of fire-cracked stone and charred earth left behind after repeated episodes of water-heating, most likely during the Bronze Age. They tend to appear in ones or twos near streams or boggy ground, so finding a cluster of seven in close proximity is a markedly odd arrangement, one that raises more questions than the landscape readily answers.

The example at Coolnahane sits in pasture on the eastern side of a stream, which is typical of the type; water was central to however the site was used, whether for cooking, processing hides, or some other purpose that archaeologists continue to debate. The mound itself is modest in height, just over half a metre, but reasonably substantial in footprint, measuring nine metres east to west and thirteen metres north to south. Its opening, nearly five metres wide, faces east, giving it the characteristic horseshoe outline that makes these features recognisable even after several thousand years of silting and slumping. The six neighbouring fulachta fiadh share the same general area, and the concentration implies sustained or repeated activity at this particular spot over some considerable period, though precisely what drew people back here, again and again, is not recorded in the ground.