Known as Grave 7 in the excavation schema, it is a cist, a box-like stone burial container, of notably irregular construction: an east sidestone, two overlapping north endstones, a south endstone, and two capstones on top, but no west sidestone at all. Inside, the fragmentary and disturbed skeletal remains of a human infant of about eighteen months were found. Beneath the cist floor, fragments of charcoal were recovered, one possibly from poplar or willow, another likely from yew.

The cairn was excavated in 1932 by the Third Harvard Archaeological Expedition in Ireland, led by Hugh O'Neill Hencken, who subsequently restored the monument. Hencken catalogued multiple burials across the site and offered an explanation for the cist's missing west wall: it appears to have been built directly against the external packing-stones of a double cist immediately to the west, a larger burial later radiocarbon-dated to around 2000 cal BC. The physical relationship between the two structures led Hencken to suggest they were contemporary. Later researchers, Brindley and Lanting writing in 1992, were not so certain. Unable to obtain a radiocarbon date for Grave 7 directly, they placed it within a broader, later phase of mortuary activity at Poulawack, tentatively dated to the mid-second millennium BC. This phase also appears to have encompassed several other cists and burials across the cairn, suggesting the site accumulated its dead over generations rather than in a single episode of construction.