It measures roughly seventeen metres north to south and thirteen metres east to west, rises to about ninety centimetres at its highest point, and opens toward the northwest with a gap of just over five metres. It is made of burnt material, dark and crumbly, and it has been there for somewhere between three and four thousand years.

This is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, with Cork particularly well supplied. The basic principle was straightforward: dig a trough near a water source, line it with wood or stone to hold water, heat rocks in a nearby fire, then drop the hot rocks into the trough to bring the water to a boil. The discarded, fire-cracked stones accumulate over time into the characteristic horseshoe mound, with the open end typically facing the water or the original trough. The Irish Bronze Age landscape was dotted with these sites, many of them seemingly used seasonally or intermittently, often near streams exactly like the one here. The Kilknockan example follows the classic form closely, its opening oriented toward the northwest, the mound intact enough after millennia to still read clearly as a structure rather than a natural feature.