Llanwnda 8 is a Scheduled Ancient Monument, first noted in its present location in 1883. It is built into the field bank at the south-east corner of the crossroads opposite the modern cemetery, some 0.6km south-east of St Gwyndaf's Church (NPRN 308468). Between 1956 and 1954 it was moved further back into the field bank and surrounded by protecting walls. The stone is one of eight early medieval cross-carved stones associated with the church (see NPRNs 422430-422435 & NPRN 421734), suggesting it was an early ecclesiastical site of some significance.

The stone is a rough, unshaped boulder of epidote-rich gabbro. Only one face is visible, obscured by lichen and very weathered. It is carved in false relief with a double-outline Latin cross, thought to be 9th- to 11th- century in date. The cross is similar in style to Llanwnda 2 (NPRN 422431). . The stone may have marked the approach to St Gwyndaf's Church or boundary associated with the site. Another stone, Llanwnda 11 (now lost), was reportedly found at Pont Eglwys (some 760m to the west-southwest of the church) and could have performed a similar function.