The structure at Corimla sits in ordinary, undulating pasture on the south-eastern flank of a low rise in County Mayo, with open views stretching to the east and south. It is not the kind of monument that announces itself: six earthfast upright boulders and large stones outline a roughly rectangular chamber or gallery, oriented north-west to south-east, measuring between four and a half and five metres in one direction and about 1.8 metres across. The stones stand to a fairly consistent height of around half a metre, with gaps between them ranging from a few centimetres to one and a half metres, giving the structure an uneven, time-worn quality rather than any sense of formal enclosure.

Megalithic tombs of this kind were built during the Neolithic period, generally between around 4000 and 2000 BC, and were used for communal burial, often over many generations. The Corimla example is listed as unclassified, meaning it does not fit neatly into the established types recognised in Irish archaeology, such as portal tombs, court tombs, or passage tombs. The chamber sits centrally on a low, grass-covered rectangular platform measuring roughly 12.5 metres by 10.8 metres, which may incorporate the collapsed and spread remains of a cairn, the stone mound that would originally have covered the burial chamber. The platform edge is marked by a scarp, most pronounced on the southern and western sides where it reaches up to 1.5 metres in height. A large semi-prostrate slab protrudes from the eastern edge of the platform, and several metres further east a substantial boulder sits on the field surface, possibly displaced from the original structure over centuries of agricultural activity.