An ancient enclosure, long since ploughed flat, still surfaces periodically as a cropmark, the buried ditches and banks influencing how plants above them grow, tracing out a shape in the soil that no amount of tillage has entirely erased.

The enclosure appears on the first edition Ordnance Survey six-inch map of 1839, recorded as a roughly oval feature. By the time of the 1947 revision it was being described differently, as rectangular with rounded corners, measuring approximately 47 metres on its northwest to southeast axis and around 40 metres across. Whether this reflects a genuine change in how the monument was being read, or simply a difference in surveying precision, is difficult to say now. What the maps and later aerial imagery together suggest is a site of some age and local significance. One quiet piece of evidence supports this: the townland boundary running northeast to southwest immediately north of the enclosure appears to kink outwards, bending to accommodate the monument rather than cutting straight through it. Boundaries of this kind are often very old, and when they deviate around a feature, it usually means that feature was still respected, or at least still visible, when the boundary was first established. The monument was eventually levelled, and by the time an aerial photograph was taken in July 1971 it survived only as a cropmark.

Cropmarks form when buried features such as filled ditches or compacted surfaces affect moisture retention in the soil above them, causing crops to grow taller or shorter, greener or yellower, in patterns that echo whatever lies beneath. Seen from ground level, these variations are invisible; from altitude, or in satellite imagery, the geometry of a lost structure can suddenly become clear. At Annamult, that geometry is a rounded rectangle, sitting quietly in a ploughed field, its outline still faintly insisting on itself across the centuries.