It measures 76 centimetres across and is no more than ten centimetres thick at its deepest point, a flat grey disc that most visitors would probably step around without a second thought. It is, however, very likely the last physical remnant of a milling operation old enough to appear on seventeenth-century maps.

A mill is recorded at roughly this location on the Down Survey Barony map of 1656 to 1658, a Cromwellian-era cartographic project that catalogued landholdings across Ireland with unusual thoroughness for its time. By 1838, when the Ordnance Survey produced its first large-scale six-inch maps of the country, the site was marked as a Tuck and Corn Mill, an L-shaped building on the southern bank of a tributary stream of the River Deel. A tuck mill, also called a fulling mill, used water-powered hammers to pound and thicken freshly woven woollen cloth, while a corn mill ground grain between heavy rotating stones. Running both functions from a single site was common where water power was available and communities needed to process both wool and oats. The area's traditional Irish name, Baile an Mhuilinn, meaning the townland or settlement of the mill, suggests the operation was woven into local identity long before any map recorded it. Ruins were still visible in the early twentieth century, and local memory held that oats were among the crops processed here. Since then, the millstream itself has been diverted from its original course, the building has gone entirely, and the millstone in the farmyard is what remains.