Somewhere in a tilled field on a gently south-south-east-facing slope in County Limerick, a circular enclosure roughly 47 metres across sits entirely below the surface of the soil, invisible to anyone walking the ground. No earthwork rises above the furrows, no stone breaks the surface, and two separate Ordnance Survey mapping campaigns, the six-inch survey of 1840 and the 25-inch revision of 1897, recorded nothing here at all. The site exists, for practical purposes, only as a shadow.

That shadow was first noticed in 1986, when aerial photographs taken at a scale of 1:10,000 for Bord Gáis Éireann, during survey work for the Curraleigh to Limerick gas pipeline, revealed the outline of a circular enclosure in the fields at Ballinveala. Enclosures of this type, which in Irish archaeology often denote the remains of a ringfort or an early medieval settlement boundary, typically comprise a circular bank and ditch; when those features are levelled by centuries of ploughing, the disturbed soil above the buried ditch retains moisture differently from the surrounding ground, causing the crops grown over it to ripen at a slightly different rate. The result is a cropmark, a faint difference in colour or height in a growing cereal crop that becomes legible from the air under the right conditions. The Archaeological Survey of Ireland visited the site in 2000 and confirmed that no surface remains were visible. The enclosure measures approximately 39 metres in internal diameter and 47 metres externally, dimensions consistent with a medium-sized ringfort, though no dating or further investigation appears to have followed. A Google Earth orthoimage captured on 28 June 2018 shows the cropmark still clearly present.

For anyone curious enough to seek it out, the site lies about 200 metres west of the townland boundary with Shanaclogh. Because it has no physical presence above ground, there is nothing to examine on foot; the field is working agricultural land and should be respected as such. The cropmark is most likely to be visible in aerial or satellite imagery taken during a dry spell in late June or July, when a growing cereal crop is at its most responsive to variations in soil moisture below. The 2018 Google Earth image, taken on 28 June, is the most recent confirmed sighting and gives a reasonable sense of what to look for online if not on the ground.