Found in an 'abandoned' shepherds hut near Mynachlog-ddu. 'The Opened Book' in the picture is the Bible; the passage is Numbers Chapter 3 & 4.
According to Charles, B. G. (1992) in 'The Place names of Pembrokeshire' in National Library of Wales. p. 124 -Mynachlog-ddu means "black monastic grange" (the literal translation is ''Monastery-black'')
Before the Dissolution of the Monasteries, the parish belonged to St Dogmaels Abbey. The 'Black Monks' were Benedictines and the Abbey of St Dogmael’s was a Benedictine Monastery.