The marks, each roughly two centimetres in diameter, were possibly punch-struck into the stone, a technique associated with prehistoric rock art in which a harder implement is repeatedly driven into the rock face to produce shallow cupmarks or pits. The boulder itself is modest, measuring just under a metre across, and part of its surface has been lost, meaning the original pattern may once have been more extensive. What survives is quietly arresting: deliberate, repetitive, and almost entirely unexplained.

Rock art of this type is notoriously difficult to date with precision, but comparable examples in Ireland are generally attributed to the later Neolithic or Bronze Age, a span running roughly from four thousand to about seven hundred years before the common era. The Threewells boulder was noted by Liam Price in 1946, and more recently by Chris Corlett in 2013, placing it within a broader county-wide picture of such markings in Wicklow. The site was also selected for study by the Wicklow Rock Art Project, run through the School of Archaeology at University College Dublin under Dr. Clíodhna Ní Lionáin, whose team produced a photogrammetric three-dimensional model of the surface, a technique that uses overlapping photographs to render fine surface detail digitally and allows researchers to study the marks without repeated physical contact with the stone.

The boulder sits on a gentle south-east-facing slope in a small field, a setting that is entirely ordinary to look at but consistent with how many examples of Irish rock art were placed, on open ground with a degree of aspect rather than concealed or elevated. The rows of holes are small enough that they would be easy to miss without knowing to look for them.