Individually they are just carved blocks. Together, they are the scattered remnants of a curved opening that no longer exists, a quiet puzzle in stone about what the building once looked like and what has since been lost.

Voussoirs are the interlocking keystones of an arched doorway or window, cut at an angle so that each one locks against the next under the pressure of its neighbours. When an arch collapses or is dismantled, these shaped stones tend to survive precisely because their unusual geometry makes them hard to repurpose. That four of them remain inside St Finan's chancel, rather than having been carried off or built into a later wall, suggests some continuity of care, or at least of neglect undisturbed enough to leave them in place. Church Island itself is associated with the early medieval monastic tradition that took root on Kerry's islands and lake islands, and St Finan's is one of several small churches in the region whose fabric spans centuries of use and gradual decay.