Vulture Mask

The vulture mask's general purpose is to protect the weak spot of the vulture: Its face. It can be obtained by hitting the vulture's mask with a spear right, or knocking it off with a powerful enough explosive. Be careful, however, because vultures that have been unmasked are twice as persistent and violent. After it's knocked of the vulture or from his dead corpse, you can pick it up and use it as a shield. (needs confirmation) Occasionally slugcat will hold the mask in front of his face. The mask seems to frighten away lizards.

The lore of rainworld. (link of evidence provides info about the vulture masks lore.)

The lore behind the bone masks:

Blue Pearl - Industrial
It's a production record of a mask factory, for what seems to be its last time in service. Have you seen a bone mask? Likely not, they are all gone with their owners.

In ancient times the masks were actually about showing spiritual persuasion - covering the face as a way symbolically abate the self. Then of course, that was quite subverted as excessively ornate and lavish masks became an expression of identity. Some public persons did have problems with narrow doorways.

Originally monks in a temple would make the masks using bone plaster, and when the production was automated it would generally remain on the same site. So that the old stones could...radiate the material with holiness, I suppose.

This is from one such facility called Side House, which was here on Pebble's grounds. In the iterator projects many old industrial-religious sites like this were remodeled and incorporated. I think this one was made to provide pellets of holy ash to Pebbles, but knowing him he probably hasn't used much of it!~ Big sister Moon.

Conclusion.

This shows that the owners may have been the vultures and the fact that the masks posses their identity may indicate why they get attacked by fellow vultures if they don't wear their masks. a form of racism. But this also says why the lizards fear the vultures, its in their masks. when a vulture loses his identity, he is forgoten, laughed at and bullied to hell and back.

Trivia

 * Slugcat will turn to mask to the air when eating.
 * Slugcat occasionally holds it like a shield.
 * It needs to be held and cannot be swallowed/regurgitated for storage.
 * scavengers and lizards will attack you less likely if you have it.