This is a fulacht fia, a type of prehistoric cooking site found in great numbers across Ireland, typically Bronze Age in date. The basic principle was straightforward: stones were heated in a fire and dropped into a water-filled trough, bringing it to the boil. The repeated fracturing of those stones, cracked by sudden heat and cold, produced the characteristic horseshoe-shaped mounds that survive in their hundreds in fields just like this one.

The Grange example was noted by Lee in 1932, who described it as roughly three feet high at its centre, sloping gradually down to the level of the field around it. That modest profile is fairly typical of the form, and the spread of burnt material observed at the site is consistent with how such mounds accumulate over repeated use, discarded stone and ash building up into the gentle rise that Lee recorded. The mound has sat in agricultural land since at least that early-twentieth-century observation, and presumably for a great deal longer before anyone thought to write it down.