A fulacht fia, the term used for these ancient burnt-mound sites found widely across Ireland, typically consisted of a mound of fire-cracked stones accumulated beside a water-filled trough; stones were heated in a fire and dropped into the trough to boil water, presumably for cooking meat. At Shanvaghera, that mound survived as a roughly circular spread about ten metres across and half a metre deep, composed of heat-shattered stones and charcoal, sitting on an area of low gravel ridges threaded with shallow, wet valleys.

The site came to attention during archaeological monitoring carried out in advance of the construction of the Knock-Claremorris Bypass, Phase 2, and was excavated in 2000 by Zajac under licence 00E0727. Land reclamation had already partly levelled the mound, and drainage channels had been cut through it, so what survived was a reduced but still legible record. Beneath the mound, slightly east of centre, excavators uncovered a trapezoidal trough set into boulder clay, measuring roughly 1.8 metres on its long axis and about a metre across. It had been carefully constructed from timber planks, predominantly of alder, with one end plank of willow, and a wooden peg of hazel pinned the eastern end in place. The choice of locally available wetland timbers is entirely consistent with a boggy setting. Among the material recovered from the fill of the trough were hazelnut shells, three fragments of animal bone, and a possible whetstone, small details that suggest something of the activity that once took place around it, even if the full picture remains incomplete.