Large skull
Sorry but Im not able to answer your question but I’m pretty sure that after this post the prices will rise :P
I do know they make the godskull stuff.
They also may be used to make the godskull recipes.
http://www.gw2db.com/search?search=godskull
Godskull weapons surely aren’t the reason for the item to be in game (and of rare quality). I expect their price to skyrocket one day so I’ve been stockpiling them whenever I got some extra money (I’m actually doing that with all rare mats below 1s).
I do know they make the godskull stuff.
They also may be used to make the godskull recipes.
http://www.gw2db.com/search?search=godskull
The recipes are bought with karma in Fireheart Rise.
The only item that I have seen that uses these skulls in the mystic forge is a Skull shaped focus… I don’t think any other recipes have been discovered yet. I’ve always wondered what else could be made though, I just don’t have the variety of materials needed to check myself.