A chambered tomb, set in a disturbed area, c.70m E-W by 24m, possibly resulting from quarrying activity.
Two upright stones, 1.1m & 0.8m high, and a broken slab, 2.0m by 1.0m, along with other large stones, are set in a one of a series of hollows.
Coflein has an ariel picture, I think this ruined burial chamber is in or near the D shaped thing on top of light coloured field.
coflein.gov.uk/en/site/276052/images/LOWER+TREGENNIS+BURIAL+CHAMBER/