Beneath the turf, however, lies something rather more arresting: a dense layer of oyster shells packed into dark brown soil, roughly ten metres long and half a metre deep. This is a midden, the accumulated food waste of prehistoric people, and the shell and soil compressed beneath the sod here has been sitting undisturbed, more or less, for somewhere between five and six thousand years.

A radiocarbon date taken from this midden in 2000 returned a calibrated result of 3,660 to 3,440 BC, placing its use firmly in the Neolithic period, when farming communities were beginning to establish themselves across Ireland but coastal foraging remained a significant source of food. Oysters, evidently, were on the menu in quantity. This particular deposit is one of seven middens identified along a 1.3-kilometre stretch of the same shoreline, spread across the townlands of Tanrego West and Tanrego East, with a further cluster in Carrowmore. That concentration suggests this was not a casual campsite but a coastline regularly returned to, season after season, by people who knew exactly what the bay could provide. When the site was inspected in 1994, the deposits were found to lie directly beneath the modern sod layer, resting on sandy soil below, a rare instance of prehistoric material surviving so close to the present-day surface with relatively little disturbance.