It is more likely that the octopus/spider on de Chèrisey's fake tombstone is partly based on a drawing found in the works of French esotericist Paul Le Cour (1871-1954). Pierre Plantard modelled certain elements of his Priory of Sion mythology on Le Cour's writings and had also quoted Le Cour in his 1940s journal, Vaincre.

To Paul Le Cour, the octopus symbolised the demiurge – representing an esoteric version of Jesus Christ (Jesus Christ is sometimes traditionally compared to an octopus because of the 9 manifestations of the Spirit – Christ Himself + 8 tentacles, and the French word poulpe/pulpe also means flesh – Christ was the Word made Flesh). The similarity is unmistakable.

When Philippe de Chèrisey created his artistic depiction of the fake tombstone of Marie de Negri d'Ables, he worked on the pun araignée (French word for spider) and Or à Rennes (the gold at Rennes) – the letters PS on the fake tombstone are enclosed in a loop and a vertical line with an arrow-head at each end linking the letters with the word PRAE-CUM (before) – the letter before P is O and the letter before S is R – the two combined letters therefore spell the word OR.

At the time, Pierre Plantard must have said to Philippe de Chèrisey: “Make that spider also look like an octopus”..... The drawing therefore ended-up as a stylised version of both an octopus and a spider.

This is the most likely explanation, with the octopus in St Sulpice being a mere coincidence.

Below, emblem of the Eucharist as an octopus, from Emblemes sacrez sur le tres-saint et tres-adorable sacrement de l'eucharistie by Augustin Chesneau, Augustin Lubin, Albert Flamen and Florentin Lambert, page 128 (Paris: Chez Florentin Lambert, 1667)