That ambiguity is, in its own way, the whole story. A crannog is an artificial or partially artificial island, typically built out into a lake or marsh during the early medieval period and used as a defensible dwelling place. What exists at Derryronan is considerably more uncertain: a local report, a depression in the ground, and an entry in two national registers of protected monuments.

The site came to official attention when reclamation works were carried out in the area and someone local reported seeing what appeared to be the remains of a crannog. That account was enough to have the possible site listed in the Sites and Monuments Record in 1991 and the Record of Monuments and Places in 1995. Those two registers exist to flag locations where archaeological significance is suspected, whether or not physical evidence has been formally confirmed. The natural depression in the boggy ground where the remains were reportedly observed sits in terrain that would have been well suited to crannog construction, low-lying, waterlogged, and difficult to approach on foot. But no visible trace survives at ground level today, and no excavation appears to have followed the original report.

What remains is essentially a question mark written into the landscape. The reclamation work that first drew attention to the site may also have disturbed or obscured whatever was there. It is a reminder that a significant portion of Ireland's early medieval archaeology exists in this state, known only through local memory, glimpsed briefly during drainage or construction, and then covered over again.