That absence is quietly unsettling. Most prehistoric and early medieval enclosures preserve at least a gap or a causeway to indicate where people passed through; here, nothing of the sort survives, leaving the boundary itself as the only legible feature.

The enclosure is roughly subcircular, measuring approximately 67 metres north to south and 70 metres east to west, dimensions that place it comfortably within the range of early medieval ringforts or their precursors, though no firm date has been established for its construction. Along the northern edge it is defined by a low bank; elsewhere the boundary takes the form of a scarp, a natural-looking slope cut or shaped to mark a limit. To the west there is also a fosse, a defensive or boundary ditch roughly four metres wide. What makes the interior particularly striking is a children's burial ground tucked into its south-western quadrant. These are known in Ireland as cillíní, informal burial places used from the medieval period into the nineteenth and twentieth centuries for unbaptised infants and others excluded from consecrated ground. Their presence inside older enclosures is not uncommon; the pre-existing earthwork may have lent a sense of ancient sanctity to the spot, or simply provided a discreet boundary. The combination of an undated enclosure, an unlocated entrance, and a cillín gives Ballylusk a layered, somewhat muted strangeness that rewards attention even if it resists easy explanation.