This modest monolith measures 1.3 metres in height and presents a rectangular footprint of roughly 40 by 36 centimetres at its base. The stone's placement on relatively level, marshy terrain is characteristic of many prehistoric monuments across Donegal, where ancient peoples deliberately selected such locations for reasons that continue to intrigue archaeologists today.

Standing stones like this one represent some of Ireland's most enigmatic archaeological features, dating primarily from the Bronze Age period between 2500 and 500 BCE. Whilst their exact purpose remains debated amongst scholars, these monuments likely served multiple functions within prehistoric communities; territorial markers, commemorative memorials, or astronomical alignment points for tracking seasonal changes. The waterlogged conditions surrounding this particular stone have likely helped preserve it through the centuries, as the acidic bog waters tend to discourage the growth of vegetation that might otherwise topple or obscure such monuments.

This stone forms part of Donegal's rich archaeological landscape, documented comprehensively in the 1983 Archaeological Survey of County Donegal by Brian Lacey and his team of researchers. Their meticulous cataloguing of the county's field antiquities, from Mesolithic sites through to 17th century remains, has proven invaluable for understanding how successive cultures have shaped this northwestern corner of Ireland. The standing stone at An Bearnas Íochtarach, though unadorned and relatively modest in scale, serves as a tangible link to the prehistoric communities who first began transforming Donegal's wild landscapes into places of human significance.