>>281712587
They enter the sixth layer, and there is a whole ordeal with them eating half-developed, wriggling fetuses out of eggs that they gathered. Near the village arc's end, babies being eaten is pivotal. What's more, there are the wish-granting eggs bound up in the same story arc, and the fetuses are eaten out of eggs. There are no less than two similarities between Riko and co. eatung the fetuses out of the eggs and the Ganja squad eating fetuses that were born from an egg.
As for the scat, the village arc OPENS with Riko and Meinya taking a big shit, then Riko almost lies down next to shit, then Riko eats something weird and gets diarrhea from it, then Riko has a flashback to Jiruo being like "Hey, drink water when you get diarrhea, dysentary actually kills cave raiders," then we get a whole flashback arc in which dehydration and diarrhea are PIVOTAL in deciding the fate of the ganja squad, in causing the village to come into being, and in transforming everyone. Tsuc likes bathroom stuff enough that maybe that would be a looser connection than the baby-eating thing, but there are so many parallels, and Jiruo's "hey, this might happen" is SO on-the-nose, that it doesn't feel like coincidence.
Tsukushi included mirrored elements between the flashback and what happens in the present. To say that it's coincidence, or that it's nothing to read into, would be silly. If you want to be completely pedantic about this and say that this isn't foreshadowing or the introduction of thematic elements, then please give me the proper literary terminology for whatever this actually is. That classical literature degree clearly isn't giving me any help, so please fill me in on what this is if not foreshadowing.