Fake "tombstone" created by Philippe de Chérisey during the early 1960s as part of his puzzle for his large "parchment", wrongly ascribed to Eugène Stublein (there is no evidence that Stublein had any secondary interest in engraved tombstones of the Languedoc) – see:
‘Priory of Sion: The ‘Et In Arcadia Ego’ Tombstone’
http://priory-of-sion.com/pos/stublein.html