A fulacht fia, the plural being fulachtaí fia, is a type of prehistoric cooking site found in enormous numbers across Ireland, typically consisting of a horseshoe-shaped mound of fire-cracked stone beside a water source. The standard interpretation is that stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil, with the cracked and spent stones accumulating into the distinctive mound over repeated use. The Killeens example sat on the northern side of a stream, in overgrown ground, which fits the pattern almost exactly.

The site was noted by the archaeologist M. J. O'Kelly in 1954, at which point it was apparently still recognisable. O'Kelly was one of the central figures in mid-twentieth-century Irish archaeology, later famous for his excavations at Newgrange, and his references to individual sites like this one were part of a broader effort to catalogue what remained in the landscape. By the time Walsh recorded it in 1985, the mound had been levelled. Whatever accumulation of burnt stone and charcoal had survived from the Bronze Age had been dispersed, most likely through agricultural clearance or land improvement. The stream is still there, presumably, but the archaeology is gone.