Yet this steep-sided mound of limestone rubble, measuring nearly 25 metres across at its base and standing over six and a half metres high, sits at what may once have been a charged boundary in the early medieval Irish world. When John O'Donovan visited in 1839, he recorded it as roughly a hundred paces in circumference and about twenty-five feet tall, though Thomas Johnson Westropp, writing in 1905, put its height somewhat more conservatively at twelve to fourteen feet. The discrepancy says something about the cairn's condition over time: it has been robbed at the west and south, and low drystone walls extending from the monument on three sides were probably built from the loose collapsed material, repurposed as animal shelters by later farmers. Cultivation ridges still show up around the monument in aerial photography.

The name is the key to the cairn's deeper strangeness. O'Donovan recorded a local tradition in which a multitude of Connachtmen pursued a great serpent from their own province all the way to this spot in Clare, killed it there, and each threw down the stone he had been carrying in the chase, building the heap that remains. The name Carnconnaughtagh, meaning roughly the cairn of the Connachtmen, preserves that story. But O'Donovan also proposed a more historically grounded identification, connecting the site with Carn Mhic Táil, a place mentioned in early Irish sources in association with the Corcu Modruad, the people from whom the baronies of Corcomroe and Burren take their names. He suggested it was probably the place where the chief of Corcomroe was inaugurated, in the formal outdoor ceremony, typically held at a tribal assembly site, through which an Irish king took power. The scholar Elizabeth FitzPatrick, writing in 1997, found no direct textual evidence of inauguration at the site but noted its appearances in the sources as a gathering and mustering place, which, combined with its ancestral associations via the figure of Táil, makes the case plausible. She further argued that the cairn may have taken on new ceremonial weight in the first half of the eighth century, when the Dál gCais drove the Corcu Modruad from much of south and east Clare, leaving Carn Mhic Táil as a prominent landmark on the southern edge of the kingdom that remained to them, and perhaps a site where the assertion of continuity and legitimacy mattered all the more.