What they found was a fulacht fia, a type of prehistoric cooking site common across Ireland, typically consisting of a water-filled trough, a hearth, and a mound of heat-shattered stone. The stones would be heated in a fire and dropped into the water to bring it to the boil, and the resulting dump of cracked, burnt rock is often all that survives. At Lusk, enough survived to tell a more detailed story than most.

The 2003 excavations, carried out in advance of development and later published by E. Larsson in 2006, identified a total of 89 features across the site. The fulacht fia itself appeared as a spread of charcoal-rich soil and burnt stone measuring five metres in length and 3.4 metres in width. Beneath two distinct layers of that burnt stone material, excavators found something less expected: a well-preserved deposit of organic material, including leaves, nuts, and other macro-fossils, plant and biological remains that survive in identifiable form. Organic material rarely endures in Irish soils, which makes its presence here, sealed beneath the stone dumps, particularly useful for understanding the site's environment and chronology. In the south-west corner of the site, an earth-cut trough was also recorded, accompanied by stake-holes, the traces of upright timber posts that may have supported a wooden lining or some kind of temporary structure over the working area.

The site at Lusk is not accessible as a visitor destination; it was excavated ahead of development and the findings exist now primarily in the archaeological record rather than in any visible monument on the ground. For those interested in fulachtaí fia more broadly, the National Museum of Ireland holds material from many such excavations, and the wider landscape of north County Dublin, low-lying and well-watered, is precisely the kind of terrain where these sites cluster. The Lusk example is a reminder that the ordinary-looking fields between towns often contain far more than the surface suggests.