It is penannular, meaning it forms an almost complete ring rather than a solid mound, with a deliberate gap opening to the west. That gap, and what was found beneath the stones, set this structure apart from a straightforward burial monument and leave its original purpose genuinely unclear.

Before excavation in 1955, the site presented itself as a plain oval cairn, roughly 14.8 metres long and 13.4 metres wide, with noticeable accumulations of stone at its northern and southern ends. It formed part of a wider archaeological grouping known as Baile na mBocht. When Goulden excavated the site that year, the outer dimensions resolved into a penannular form measuring 14.2 metres by 11.2 metres, and beneath the disturbed stonework lay a flagged floor associated with quantities of shell and bone. The shell and bone suggest sustained activity, possibly occupation or repeated use over time, but the site had been too heavily disturbed before Goulden's work for the original layout to be recovered with any confidence. George Henry Kinahan had noted the site as early as 1869, and it was later recorded by Tim Robinson in 1980, whose meticulous mapping of the Aran Islands and Connemara brought many such features back into wider awareness. The archaeological record, as summarised by John Waddell in 1988, reflects a monument that was once more legible and is now, despite excavation, somewhat more ambiguous than before.