That contrast alone marks it out. The mound is roughly twelve metres across at its widest, half a metre high, and covered in sod, but beneath the surface it is composed of fire-cracked stone fragments packed into black soil, the characteristic signature of a fulacht fia.

A fulacht fia is a Bronze Age cooking site, one of the most common archaeological monument types in Ireland yet still not entirely understood. The typical arrangement involved heating stones in a fire, dropping them into a water-filled trough to bring the water rapidly to the boil, and using that to cook meat. The spent, shattered stones were raked aside after each use and piled up, which over centuries produced the low, horseshoe or kidney-shaped mounds that survive across the Irish landscape today. At Shanvally, a shallow depression between the two arms of the mound at its south-south-west end may indicate where that trough once sat. A field drain or stream, four to five metres wide and over a metre deep, runs just fifteen metres to the south-south-west, which fits the pattern neatly: fulachta fia are almost always found close to a reliable water source. On the western side of the mound, a further shallow depression separates it from an adjacent rise edged by a low scarp, suggesting the site may be more complex than a single mound in isolation.