Fewer are aware that higher up the same mountain, tucked into the largest of its closed depressions, a separate system sits with seven separate entrances and no visitor infrastructure whatsoever. This is the cave known locally as Maze Hole, or sometimes Ailwee Upper Cave, and what makes it quietly remarkable is not its scale but a single, persistent detail: seashells, embedded in the cave sediment, nowhere near the sea.

The cave's passages run to around 140 metres in length, with a typical height and width of roughly 1.5 metres each, making for a low, close environment that is partially choked with clay and boulders. The walls are coated in flowstone, a smooth sheet-like deposit of calcium carbonate laid down by slowly flowing water, which here has formed in a soft white variety. The cave sits east of the commercial Aillwee show-cave and occupies the highest point of the depression field on the mountain. It is the seashells, though, that have attracted the most curiosity. Embedded in the sediment rather than scattered loose on the floor, they were almost certainly brought here by people rather than deposited by any natural process. Clare is not far from the Atlantic coast, and shell middens, the accumulated food debris of prehistoric communities, are common across the Irish landscape, but why shells ended up inside this particular cave, and when, remains unknown.