What exactly are "ectoplasmic worms"? It seems like something that would be understood better by someone fluent in Japanese.
You don't need to; they're exactly what it says on the tin (or tinfoil hat since we're talking about Hori); worms, made of ectoplasm (the stuff psychic researchers claim ghosts are made of). Hori may have been ranting about the spirits of the dead fetuses, though it was ambiguous anyway, as was just about everything else he said.
It is entirely possible that he was seeing the complex knot patterns that the other psychics were seeing, and interpreting them as writhing piles of worms.
It may also be how Kagutaba's looks in a spiritual sense - or be a way of visualizing his influence as tentacles swarming all over Japan.
Due to their being dozens of Kagutaba faces in the Ominous Visual Glitch at Hori's house, it could also be interpreted that Kagutaba is only one ectoplasmic worm in a plane of reality containing dozens, hundreds, or even thousands.
The mask representing Kagutaba seen in the ritual clearly has a wound on the top of it's head - in the exact spot where Hori would strike Junko's son with a stone, despite the mask presumably being designed decades or centuries prior to Hori's birth. How on Earth is this possible? Did the mediums communing with Kagutaba foresee this event? Was Hori compelled by Kagutaba to strike in that exact spot for some reason? Is there some form of Stable Time Loop in play, possibly hinted at by Kana being aware of the film's Downer Ending before it happens?
