Three of them are arranged exactly two metres apart from one another, forming a near-perfect equilateral triangle. A fourth lies roughly twenty metres to the south-west, now absorbed into a field boundary fence, as if the landscape gradually grew around it without quite knowing what to do with it.

Boulder burials are a monument type largely confined to south-west Ireland, consisting of one large, often massive, capstone resting on smaller support stones, beneath which human remains were sometimes placed during the Bronze Age. At Derrymihin, each monument in the triangular grouping has its own character. The easternmost is the largest of the three, its cover-stone measuring 2.2 metres by 1.6 metres and roughly 0.9 metres thick, with three support stones still visible underneath. The northern monument carries a somewhat slimmer capstone, 1.7 metres by 1.3 metres, resting on two supports. The western one, nearly square at 1.5 metres by 1.5 metres, sits on a single visible support stone. The fourth boulder burial, now caught up in the field fence, has a cover-stone of 1.9 metres by 1.7 metres and retains two support stones. The arrangement of three as a triangle is particularly unusual; most boulder burials occur singly or in loose pairs, and the deliberate geometry here, if it is indeed deliberate, has no straightforward parallel. The site was catalogued by Seán Ó Nualláin in 1978, whose survey work across Cork and Kerry did much to bring these understated monuments into serious archaeological focus.