It measures roughly 16 metres from west to east and just over 6 metres across, rising only a little above the surrounding ground, and a single boulder juts from its surface slightly east of centre. What makes it quietly strange is not its size or shape, but its absence from cartographic memory: no edition of the Ordnance Survey six-inch maps, which recorded even modest earthworks across Ireland with considerable diligence from the mid-nineteenth century onwards, ever acknowledged it.

The mound sits atop a small ridge with open views south over Killala Bay and north towards the mouth of the Palmerstown River. Its western end is relatively squared off, while the eastern end curves more gently. The profile is not uniform either: it stands only about 0.3 metres above the ground at its north-northeastern edge, rising to around 0.65 metres at the south-southwestern end, suggesting either deliberate construction or the slow, uneven work of time on something older. What it was built for, if it was deliberately built at all, remains uncertain. What is clear is that it sits within a genuinely dense prehistoric landscape. Within 200 metres of this unexplained mound lie a mound barrow, a ringbarrow, a rath, and at least one other mound. A barrow is a burial mound, and a rath is a circular enclosure, typically of the early medieval period, formed from earthen banks. The ringbarrow nearby combines elements of both traditions. Together, these features suggest this corner of Mayo was a place people returned to, marked, and shaped over a very long period, even if the mound itself refuses to declare its purpose.