The term is one of the most widespread in rural Irish tradition, applied to enclosures like this one across the country, and it reflects a long-standing popular belief that such structures were inhabited or protected by supernatural forces. That belief, however superstitious it may seem, had a practical consequence: it kept countless enclosures from being ploughed or quarried away, and many survive today precisely because people were reluctant to disturb them.

The enclosure at Knockatillane is modest in scale but carefully proportioned. Its bank reaches a maximum height of 0.85 metres and a width of around 4.2 metres, enclosing a roughly circular interior with an internal diameter of about 7.6 metres. A narrow entrance, just 1.25 metres wide, opens at the west-north-west. No internal features have been recorded, which is not unusual; the interiors of such enclosures were often cleared or simply never built upon in a way that left durable traces. What is slightly more unusual is the raised spur of land that projects north-westwards from the site for approximately seven metres, sitting only ten to fifteen centimetres above the surrounding ground. Its relationship to the enclosure is unclear, though it may represent a remnant of an associated earthwork or boundary feature. The survey was carried out by Sullivan in 1994, and at that point the site appeared largely intact.