These are the remains of a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically Bronze Age in origin. The standard interpretation is that a trough was dug into the ground near a water source, filled with water, and then heated by dropping fire-cracked stones into it until the water boiled. The burnt and shattered stones were discarded to the sides over time, gradually building up into the characteristic horseshoe or kidney shape that survives today. The association with boggy ground and nearby water is entirely typical; here, a small pond sits immediately to the north of the larger mound.

The site at Ardrahan actually preserves two separate mounds in close proximity, which is less common and adds some interest to what might otherwise seem like a featureless patch of bog. The larger of the two measures roughly nine metres across and rises to about 1.3 metres above the surrounding ground, with a gap of five metres opening to the south, just inside which a small depression of around 1.6 by 2.3 metres is visible. This hollow likely marks where the trough once was. Immediately to the south sits the smaller companion mound, measuring 6.5 by 5.5 metres and reaching 0.9 metres in height, with its own depression of roughly three by two metres along its crest. The details were recorded by C. Toal in the North Kerry Archaeological Survey, published in 1995, which documented the wider pattern of prehistoric activity across this part of the county.