The one at Poulgorm in County Clare is neither. Sitting on a narrow north-south ridge above deep hollows on either side, this structure is markedly rectangular, measuring roughly 33 metres north to south and 29 metres east to west, with walls that once stood as solid dressed stonework and corners that are noticeably angled rather than simply squared off.

The antiquarian Thomas Johnson Westropp, writing in 1911, singled it out as a "remarkable straight sided 'moher'... built of long slabs", using the Irish term for a type of stone enclosure wall. He observed that while a few other cashels share this straight-sided form, the angled corners here were unusual enough to suggest a later date of construction than the typical early medieval examples. By 1996 it had been catalogued officially as a rectangular enclosure, which somewhat undersells it. The walls, now grass-covered and spread to between 2.5 and 5 metres wide, still retain visible stone facing on all external faces and on parts of the interior. Where the original masonry is legible, the wall thickness ranges from 1.7 metres on the east side to 2.7 metres on the north. The original entrance position is uncertain, though the south wall is considered the most likely candidate. More recent drystone walling has been laid on top of the cashel walls on three sides, and a farm track has clipped the northeast corner. Inside, grass-covered divisions trace the outline of a later field system that reused the enclosure. The cashel sits within a broader ancient field system and is immediately adjacent to an oval enclosure, itself containing a separate subcircular cashel, suggesting this was once a more complex and layered landscape than its current appearance implies.