The pit itself is modest almost to the point of invisibility: roughly sixty centimetres across and forty centimetres deep, bowl-shaped, packed with charcoal suspended in a grey-brown clay. Nothing about it announces itself. And yet that compactness, that contained darkness in the soil, is precisely what drew attention during preparatory work at Greenfield before road-building swallowed the site.

In 2001, test-trenching carried out ahead of construction of the N22 Ballincollig Bypass turned up an anomalous concentration of charcoal-rich clay. Excavation directed by Murphy that same year confirmed the feature as a hearth, one of the simplest and most ancient of domestic or industrial structures: a deliberately dug pit in which fire was maintained, the bowl shape helping to concentrate heat and retain embers. A charcoal sample from the fill was submitted for radiocarbon analysis, which returned a calibrated date range of AD 250 to 580, placing the hearth somewhere in the later Roman Iron Age or early medieval period in Irish terms, a time when Roman influence flickered at the edges of the island without ever quite taking hold, and when small rural communities were beginning to leave the traces that later archaeology would slowly piece together. The identity of whoever kept this fire, what it was used for, whether it warmed a dwelling or served some craft or processing purpose, is not recoverable from the pit alone.