Voussoirs are the wedge-shaped stones that form an arch, each one cut at an angle so that the pieces lock together under their own weight. That these four survive at all, detached from whatever arch they once composed, gives them a particular kind of interest: they are fragments of a structure that no longer exists in its original form, traces of a more elaborate building than what now stands.

The church is dedicated to St Finan, and Church Island itself sits in Lough Currane, a lake in south-west Kerry long associated with early Christian activity. The presence of worked architectural stonework of this kind points to a building that, at some stage in its history, had pretensions beyond simple vernacular construction. Carved arches were not universal features of early or medieval Irish ecclesiastical buildings, and the effort involved in shaping voussoirs suggests a degree of craftsmanship and intention that makes even four displaced stones worth pausing over. The scholarly record of these fragments is documented in O'Sullivan and Sheehan's archaeological inventory of south-west Kerry, published in 1996, which places them within a broader account of the island's remains.