Early in 2018, a shell midden became exposed in the eroding bank, a narrow but telling deposit sitting roughly 0.3 metres below ground level. A shell midden is essentially a refuse heap left by people who gathered and ate shellfish, and over time the discarded shells, along with organic material, compact into a distinct dark layer that can survive for centuries or millennia in the soil. This one runs to 3.4 metres in length and measures about 0.5 metres thick, a modest strip of evidence that nonetheless carries considerable weight.

The deposit is composed largely of mussel shells, with cockle and periwinkle shells also present. That combination points to intertidal foraging, the patient work of gathering whatever the shoreline offered. Cromane, a low-lying peninsula extending into Castlemaine Harbour, has long been associated with shellfish, and this midden suggests that connection has deep roots. The precise age of the deposit is not recorded, but middens of this type found along the Irish coastline range from the Mesolithic period through to more recent centuries, and even a relatively modest example like this one can yield information about diet, seasonal activity, and the human relationship with a particular stretch of coast over time.