It measures roughly four metres long, three metres wide, and only about forty centimetres high, so easy to miss entirely, especially as vegetation has long since taken hold. What it represents, however, is a type of site found in considerable numbers across Ireland, and one that continues to generate genuine archaeological curiosity.

This is a fulacht fia, a class of prehistoric cooking or processing site typically dated to the Bronze Age, though some examples are earlier or later. The defining feature is the mound itself, which accumulates over time from fire-cracked stones repeatedly heated and discarded. The usual interpretation is that stones were heated in a fire and then dropped into a water-filled trough, bringing the water rapidly to the boil for cooking meat or other purposes. Some researchers have proposed additional uses, including hide-working or even brewing, though cooking remains the most widely accepted explanation. The presence of a nearby stream at Firmount fits the pattern well; ready access to water was essential to the whole process, and such sites are characteristically found close to running water or in low-lying, naturally wet ground. The marshy setting here is entirely typical of the type.