I don't get it. I thought the other "bodies" were just split personalities like a psychological delusion in her head. How did they physically travel to "mother"? And how are they eating her mind?
@Nk9bjP4A They don't have physical bodies, since Kumoko is a spider, she has a mental link to mother and she used that to send her parallel wills to eat at mother.
As it was explained in the novel, since Kumoko is technically one of her children, Mother still has a weak psychic link to her like she does with the rest of her kids. Kumoko sent those three parts of herself to Mother through that link. So Kumoko basically emailed herself. And that email had a virus that's slowly taking over Mother by eroding her original consciousness.
So why did alba and mother stay underground? DO they like it there? Also for humans this is a berserk level world event. All her spiders and all the other monsters GG humans.
@lazerus56 it's a bit complicated and saying anything will be spoilers. This is the simplified and least spoilery as possible
Alba obeys the orders of the Dragon God Gyuri while the spider queens are the children of our cute Maou Shoujo Ariel-chan. Humanity fucked up big time and D was bored and made the world similar to an RPG for humanity to pay for their sins and because D wanted to experiment on artificially creating a god
@yohane ain't the mother spider like a few 100 meters big if not over 500m or close to 1km? The part of the labyrinth that is not under the lake isn't as deep. Sure she is in the lowest layer, but the part she is in is under land no water which a majority of the labyrinth is or at least I remember from the cross section.