A fulacht fia is, in essence, an ancient cooking or heating site, typically identified by a mound of fire-cracked stone, charcoal, and burnt material accumulated beside a trough that would once have been filled with water. Stones were heated in a fire and dropped into the trough to bring the water to boiling point, a method efficient enough to have been used repeatedly over long periods. What makes Killoran worth examining closely is how much detail survived, and what that detail reveals about how such a site was actually used.

The site came to light during topsoil stripping, which is how a great many buried monuments are discovered in Ireland, and what emerged was not a single trough but several, intercutting one another in a pattern that tells a story of repeated use and deliberate modification. Sealing them all was a horseshoe-shaped spread of burnt sandstone, silt, and charcoal measuring fifteen metres east to west and five metres north to south. The earliest trough was a sub-rectangular pit, roughly one and a half metres in each horizontal dimension and nearly half a metre deep, with a circular depression cut into its base. This depression functioned as a sump, a small reservoir within the trough itself designed to concentrate and retain the water supply. The fill of this trough contained fire-cracked stone in charcoal-rich peat, along with large flat stones that may have lined the trough's interior. A second phase of activity saw the trough recut several times, each attempt apparently trying to enlarge what had been built before, suggesting the site was returned to, found useful, and expanded by the people using it.