The fosse, the shallow ditch that once defined the perimeter of the enclosure, survives to a depth of only around ten centimetres in places, and much of the surrounding bank has been levelled over time. What was once a clearly bounded circular space has been folded into the working landscape so thoroughly that it registers less as a monument and more as a faint suggestion of one.

Enclosures of this kind are generally understood to be ringforts, the most common archaeological monument type in Ireland, built and occupied roughly between the early medieval period and the Norman arrival. They served as farmsteads for a single family or household, the surrounding bank and ditch providing a degree of security for people and livestock. At Crab, the enclosure's circular interior measures about 32.5 metres across, and the outer diameter reaches just over forty-three metres. A field boundary running north-west to south-west has been absorbed into the bank and fosse along the south-west quadrant, a detail already visible on the second edition Ordnance Survey six-inch map published in 1903, meaning that by the turn of the twentieth century the relationship between the old monument and the newer agricultural boundary was already well established. A further field boundary that once ran from the northern quadrant has since been removed entirely. There is also a small quarry cut into the interior of the north-west quadrant, measuring roughly twenty metres by six metres, which has added to the degradation of the site from within.