Its original location is formally recorded as unknown, which gives this modest stone object an odd administrative limbo: catalogued, measured, and preserved, yet severed from whatever church or site first commissioned it.

The font itself is a roughly shaped rectangular block of granite, measuring approximately half a metre long and just over thirty centimetres high. What makes it worth a second look is the contrast between the exterior and the basin within. The outer block is unrefined, almost crude in its shaping, while the interior basin is finely carved, smooth-sided, and nearly circular, cut to a depth of around thirteen centimetres. A font of this type would have held holy water for baptismal rites, and the care taken with the basin suggests it was made for a functioning church, most likely a medieval one. A short distance from Rathnew, a graveyard in the Commons townland contains both a ruined church and a second font, raising the possibility that the two objects share some common origin or history, though no direct link has been established. The Commons font and the Rathnew font are recorded separately, and the question of where exactly the Rathnew example came from remains open.