A shell midden, to use the archaeological term, is essentially a rubbish heap, an accumulation of food waste, broken tools, and other domestic debris left by people who returned repeatedly to the same spot. What survives at Currabally is modest in its present form, roughly a metre high and four metres long on the east side of a laneway running down to the shoreline, but it was once considerably more substantial.

A 1933 Ordnance Survey map shows the deposit extending westward of that laneway along the north side of nearby farm buildings. When the archaeologist Schlichting recorded the site in 1973, he described what remained as a wall some twenty-five feet long and two feet thick, sitting beside the entrance to a farmhouse. The material had clearly been reshaped and absorbed into the working landscape over the generations, its origins as a prehistoric and early medieval refuse heap not immediately obvious to anyone passing by. Radiocarbon dating of oyster shell recovered from the midden produced a result of 1150 plus or minus 50 years before present, with a calibrated date range of 701 to 950 AD, placing its use firmly in the early medieval period. Two further shell middens lie along the same shoreline a short distance to the east, suggesting this stretch of Cork Harbour was a productive and regularly exploited stretch of coastline during that era.