In a sense, that is partly what it is, which makes the story of this site more layered than its unassuming appearance suggests. A closer look at the stones protruding from its surface reveals something older: fractures caused by heat, the characteristic signature of a fulacht fia, a type of prehistoric cooking site found widely across Ireland and dating broadly to the Bronze Age. The typical method involved heating stones in a fire and plunging them into a water-filled trough to bring it to the boil, a process that left behind large quantities of cracked and fire-shattered stone, usually mounded nearby.

The mound at Capnagower measures roughly 7.5 metres north to south, 5.7 metres east to west, and rises to about 1.6 metres at its highest point on the southern side. Much of the loose, medium-sized stone that makes up the cairn appears to have been deposited as agricultural field clearance, but the heat-fractured pieces mixed through it point to something prehistoric beneath or behind all that later disturbance. Adding another layer of complexity, broad tillage ridges running on a north-east to south-west axis abut the base of the cairn on two sides, running from the mound towards the marshy basin edge. These ridges are thought to have either destroyed an earlier fulacht fia that once stood here, with its burnt stone subsequently incorporated into this mound, or the original prehistoric mound was simply used as a convenient dumping ground for cleared field stone over time. The site lies around 20 metres north-west of a separate enclosure, suggesting this corner of Clare Island saw sustained and varied human activity across different periods. The archaeology of Clare Island was examined in depth in the New Survey of Clare Island, Volume 5, edited by Paul Gosling, Conleth Manning, and John Waddell, published by the Royal Irish Academy in 2007.