Yet this discoloured patch in the grass is almost certainly the remnant of a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland and Britain. The typical form consists of a horseshoe-shaped mound of fire-cracked stone surrounding a timber-lined trough. Water in the trough was brought to the boil by repeatedly dropping heated stones into it, and the spent, shattered stones were thrown aside to accumulate into the characteristic mound. At Ballyboneill, that mound is gone.

Local memory recorded that the site originally presented as two rises with a hollow between them, a shape consistent with a paired or double fulacht fia. Both rises were levelled by machinery in 1978, leaving only the spread of burnt material that is visible now. The site had been noted before that destruction. A 1934 publication by a researcher named Bowman documented two fulachta fiadh on land belonging to E. Guerin in this townland, and the Ballyboneill site is almost certainly one of that pair. The date of their original construction is unrecorded, though fulachta fiadh are most commonly associated with the Bronze Age, broadly spanning from around 2500 to 500 BC, and they occur with remarkable frequency across the Cork countryside in particular.