It measures roughly ten metres north to south and fourteen metres east to west, rising to just under a metre in height, and it has been there, in one form or another, for thousands of years. What looks at first like a slight rise in the ground is in fact a fulacht fia, a type of ancient cooking or processing site found in enormous numbers across Ireland. The typical fulacht fia consists of a trough dug near a water source, which would have been filled with water and heated by dropping fire-cracked stones into it. Those stones, once spent, were piled to the side after each use, and it is that accumulated mound of shattered, heat-blackened material that survives into the present.

The site at Islandav appears to have been known locally for some time before any formal record was made of it. A note published in 1934 by Bowman places it on land then belonging to a J. Fitzgerald, and that early reference is the closest thing the site has to a documented history. The proximity to the stream is characteristic. Fulachtaí fia are almost always found near running water, which was both a practical necessity for filling the trough and, some researchers have suggested, a factor in how particular locations were chosen and returned to over time. The burnt mound itself is the residue of repeated episodes of use, each one adding a little more fractured stone to the heap.