It is a midden, which is an archaeological term for a refuse heap left by early inhabitants, typically composed of shellfish remains, animal bones, ash, and other domestic debris. Such deposits can be extraordinarily informative, offering a close-up picture of what people ate, how they lived, and how long they stayed in one place. This particular midden, however, is no longer visible at ground level. Whatever once accumulated here has either dispersed, been buried beneath shifting sediment, or eroded away entirely.

The site was noted by the archaeologist Göran Burenhult around 1980. Burenhult carried out extensive work in the Sligo region during that period, particularly around Carrowmore, and his observations documented features that might otherwise have gone unrecorded. The Culleenamore midden was recorded in proximity to a settlement platform, a low, artificially levelled or naturally formed area of ground that would have provided a stable base for habitation. The two features together suggest a small focus of early activity in this part of the Sligo coastline, though without the midden material itself now present, the nature and date of that activity remain difficult to pin down.