The find is modest, but its implications are considerable. Horizontal watermills, sometimes called tide mills or click mills in the Irish context, were among the earliest milling technologies used in Ireland, with examples dating back to the early medieval period. Unlike the more familiar vertical waterwheel, a horizontal mill uses a wheel laid flat beneath the millstone, driven directly by a jet of water channelled through a wooden or stone chute. The machinery was simple, the components mostly timber, which is precisely why so few survive above ground. Bogland, however, is another matter. The anaerobic conditions that make cutaway bog so destructive to the landscape are, paradoxically, ideal for preserving organic material. The mortised plank recovered here, along with a pointed wooden stake, was held in those conditions long enough to reach the twentieth century. The plank is now recorded in the Topographical Files of the National Museum of Ireland. Its location on the southern bank of the Dalgan River, close to a trackway running through the area, fits the pattern of early mill placement: water nearby, and a route to bring grain in and flour out.