It is the remnant of a fulacht fia, a type of prehistoric cooking site found in enormous numbers across Ireland, typically beside a water source. The standard interpretation is that stones were heated in a fire, then dropped into a water-filled trough to bring it to the boil, leaving behind the characteristic mound of heat-cracked, blackened material that survives for millennia. This one lies on the southern side of a stream, which fits the pattern well.

These sites date broadly from the Bronze Age, though some remain in use into the early medieval period, and they are among the most common archaeological monument types on the island. What makes the Doonasleen example quietly notable is not its survival but its partial loss. According to local information, the mound was levelled in 1986, reducing a feature that had endured perhaps three thousand years to a grass-covered scatter in the space of a single year. What remains is still measurable and still present, but the visible relief of the original mound is gone.