User blog comment:Babysync/Dust/Aura link speculation/@comment-173.255.143.228-20130823133427

For now, I (try to) believe that Dust come from mining sectors, and why there's some protest : it might be something about severe mutation due to excessive use of dust (which is cruelly thrown away due to revelation of Aura in episode 6) or the dangers to environment.

But there's no reason for me to not believe this kind of plot twist. thanks to Urobutcher, I can accept the idea and it might be something 'reasonable'.

Adding your idea (if you may), I think dust (the refined one) come from extraction of light soul. Pyrrha said something about Soul have the both of Light and Dark, perhaps the Grim born from soul without balance of light. kinda like Yin Yang, unbalance create disaster, which is mindless creatures with one simple reason : kill humans < perhaps that's the final objective before the victim's souls engulfed with darkness entirely?

unless there's another revelation about those black creatures kill animals, I'll keep my heart ready for another 'mindfuck' story.