What brought it to light was not an excavation but sheep, whose persistent rubbing against the bank exposed a layer of burnt stone at least 3.8 metres long and 0.4 metres thick, with further heat-shattered fragments visible in the stream bank extending upstream for another four metres.

A fulacht fia is a type of prehistoric cooking site found in great numbers across Ireland, typically comprising a mound of fire-cracked stones beside a trough or water source. The method involved heating stones in a fire and dropping them into a water-filled pit to bring it to a boil, after which meat could be cooked wrapped in straw or submerged directly. The Lecarrow example sits at a particularly constrained spot on the Dorree River, where the water has cut a channel just one metre wide between two steep-sided glacial hillocks, leaving banks rising to about 2.5 metres. The site is enclosed on most sides by higher ground, open only to the north-west where the stream widens into a small basin. That combination of flowing water, a contained hollow, and a raised terrace is precisely the kind of micro-landscape these sites tend to favour.

The north-western limit of the spread of burnt stone can actually be identified where the layer tapers out at the far end of the sheep-rubbed area, giving a rare sense of the site's boundary without any formal excavation. The full south-eastern extent is less certain, since heat-fractured stones continue to appear intermittently in the exposed stream face beyond the main concentration. What the rubbing inadvertently created is a kind of accidental section through a site that might otherwise have remained invisible beneath the turf of the riverbank.