Annie's mask is an object repeatedly shown in the comic, typically inside the ether. It seems to be used primarily as a symbol, as it is never shown as a corporeal object within the real world.
The mask seems to symbolize Annie's desire to conceal herself from others, both literally and metaphorically.
In Chapter 38: Divine
Annie's mask is a major symbol of Chapter 38.
- Jones gives Annie the mask, which probably symbolizes when she brought Annie her makeup in the forest. Annie's makeup consistently symbolizes a mask, hiding her true appearance and self from others.
- By taking off her mask in the decontamination habitat and using it to hide Kat's homework, Annie shows that she feels she doesn't have to hide herself from Kat - with the exception of the cheating, which is later confirmed when she tells Kat that the reason she never asked her for help was because she didn't want her to think she was stupid.
- Annie becomes very angry when Zimmy tries to take the mask, but is too weak to fight back, and Zimmy's vision of Annie's fire elemental spirit is holding the mask in its hand. After Zimmy punches Anthony and enters the hallucination, Annie is wearing the mask again, which shatters when Zimmy calls her father a jerk. Zimmy responds to this by saying she has her fight back, in contrast to when she took the mask earlier and nothing happened, when she commented that Annie had no fight in her.
- After Annie wakes up, Kat offers her the makeup, but Annie refuses. Given the parallels drawn between the mask and Annie's makeup, it's possible that the symbolic shattering of the mask represented her deviating temporarily from the need to cover her face. She returns to this soon enough, but it disappears again when Anthony returns and orders her to take it off.