What is their purpose ?

These Crozant-type crosses are all the more enigmatic because the majority of them have a cupule at the top.

CUPULE, subst. fem.

A.Botany A scaly or spiny organ, hollowed out in the form of a small cup, surrounding the flower, then the fruit of certain trees (oaks, chestnuts, beeches, etc.)

B. - by analogy - An object shaped like a small cup.

Source : CNRTL

Couverture du magazine Confluents de décembre 2019 de l'association ERICA

Liliane Chevallier brought back a surprising photograph from her trip to Arbanassi in Bulagaria:

A small cross with a cupule at its top, exactly identical to those of Crozant.

(see page 26 of the magazine Confluents N°38-December 2019)

See the 36 crosses with a cupule.