What makes it worth pausing over is its shape: roughly L-shaped rather than the simple circular or oval form that earthen mounds of this kind tend to take. At around 0.8 metres high, 6 metres long, and 3.7 metres wide, it is not large, but its unusual footprint and its position within an already ancient structure give it a particular quality of quiet oddness.

Ringforts, sometimes called raths, are enclosed farmstead sites typically dating from the early medieval period in Ireland, roughly between the fifth and twelfth centuries. They are extraordinarily common in the Irish landscape, with tens of thousands recorded across the country. The earthen bank and ditch that define them usually enclosed a family's dwelling and outbuildings, and internal features within them can include souterrains (underground stone-lined passages used for storage or refuge), hearths, and structural remains. The mound at Lissagriffin is recorded as a distinct feature within the ringfort, though precisely what lies beneath the grass and what purpose the L-shaped form originally served remains, on current evidence, an open question.