Here's another aspect of gloomstalker biology that has me tripped up. Being avian, female gloomstalkers lay a single egg, rarely a pair, after mating.
Now, adult gloomstalkers possess, in addition to their true skull, an avian-like external skull composed of dense bone that fits snugly over it. It consists of an upper half and lower half, each composed of two identical mirror image sections that are fused together. The upper and lower halves themselves interlock at the rear, similar to the TMJ joint in humans. It can thus be taken off and put on at will, and functions as a layer of armor to protect their actual heads, such as during friendly sparring matches or in serious combat scenarios.
Given how young gloomstalkers develop inside an egg, I'm struggling to conjure up ways for them to acquire this necessary and unique piece of armor.
I'm most interested in "how" this armor is created and "where" it comes from. I would definitely prefer if it is somehow tied to a hatchling's parents and/or its development and is grounded in reality to some extent. As magic exists in their world, this can act as a supplement, but I want to avoid it being the only explanation if possible.
Furthermore, what options would exist for repairing this armor in the event it suffers damage?
What sort of creative ways could suffice to tackle these thorns in my side? I'm all ears when it comes to suggestions.