No, it's not a Cthulhu hat. No matter what the Today show says (do you have any idea how much what I just typed, burns. IT BURNS).
It is obviously a tiara from the Esoteric Order of Dagon, as described and featured in the Olmstead Manuscript, better known as "The Shadow Over Innsmouth." Compare with this example discovered in Peru. Or this one sighted in Spain.
As in soup, precision is everything.
Of course, the ramifications of this discovery are profound. For years David Icke has been railing on about how the royal family are a bunch of shapeshifting lizards joined together in a secret conspiracy. How about slowly transforming ichthyic-batrachian hybrid monstrosities? Hmm?