What it marks is a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically identified by a mound of fire-cracked stones and charcoal left behind after repeated use. They are so common that they are sometimes described as the most frequently encountered archaeological monument in the Irish landscape, yet individual examples like this one pass almost entirely unnoticed.

The site lies to the west of a stream and just north of a quarry, a position consistent with the typical siting of fulachtaí fia near a reliable water source. The standard interpretation of these monuments is that water was drawn into a trough, stones were heated in a fire and dropped into the water to bring it to the boil, and the discarded, shattered stones accumulated over time into the characteristic mound. The Castlecooke example came to wider attention when digging to create a passage into the field cut through the deposit, exposing a band of burnt material roughly twenty centimetres deep in the western section at topsoil level. That exposure revealed how far the deposit extends into the field, though much of it remains concealed beneath soil that was dumped there at some point, obscuring the full extent of what lies underneath.