In a pasture at Knockaderry in County Waterford, nine prehistoric cooking sites lie beneath the grass without so much as a raised hump or a local story to mark them. They are, in the most literal sense, completely invisible, and apparently forgotten.

The sites are fulachta fiadh, a term used for the characteristic mounds of burnt and shattered stone left behind by a Bronze Age cooking method. The typical process involved heating stones in a fire and dropping them into a water-filled trough to bring it to a boil, after which the cracked and spent stones were raked aside into a mound. Repeated use over time produced the horseshoe-shaped mounds that survive in their thousands across Ireland. At Knockaderry, nine such features were recorded by the National Museum of Ireland in the 1950s, clustered in a broad hollow that opens out to the east, a low-lying, potentially damp setting of exactly the kind these sites favour. What happened to them between that mid-century record and now is unclear. Nothing is visible at ground level, and no local memory of them appears to have survived.

That combination, a cluster of nine sites rather than the more common isolated example, recorded once and then effectively lost to both the landscape and living knowledge, gives Knockaderry an odd weight. The hollow is still there. The pasture is still grazed. Somewhere beneath it, the burnt stones remain.