Is there an origin for the horned skull of the librarius? I mean, since Magnus was the patron of the librarian program, plausibly it would have some relation to Prospero, but I don't know that for a fact. The program was also founded with Baalite lore at its core, but I don't know that the symbol can be attributed to any Baalite tradition either.

Obviously the image of a horned skull has pagan and occult connotations IRL, but I'm interested in the fiction here. I'd like to know if there are answers to trivial things such as from where the characters are pulling things, what traditions they're drawing from.