The mound measures twenty-three metres in diameter, which makes it a substantial example of its type, and it is positioned within easy reach of a stream roughly a hundred metres to the south-west. That proximity to water is not incidental.

This is a fulacht fia, a class of monument found in large numbers across Ireland, typically dating to the Bronze Age. The term refers to a horseshoe-shaped or rounded mound formed from the accumulated waste of a repeated heating process: stones were fired in a hearth, then dropped into a water-filled trough to bring it rapidly to the boil. Over time, the cracked and discarded stones built up into the distinctive mounds that survive today. The purpose of these sites has been debated at length, with cooking, brewing, bathing, and textile processing all proposed as possibilities. What is clear is that access to fresh running water was essential, which is why fulachtaí fia are so consistently found close to streams or springs. What makes the site at Clancool Beg particularly notable is that it does not stand alone: a second fulacht fia lies just thirty metres to the south-south-east, suggesting this stretch of slope saw repeated or sustained activity during prehistory, perhaps by communities who returned to the same reliable water source across generations.