Bonemaw Scale
It looks just like bone. Best not to question the anatomy of this creature too much...
This item is in the game files but nothing in the game data gives it to players (no recipe, drop, trader, chest or world source). It is left out of lists, counts and search.
How to get Bonemaw Scale
No way to get this item appears in the game data: no recipe, drop, trader, chest or world source uses it. It is likely unused or not yet in normal play.