Interesting. They bring the worm thing up so it doesn't touch soul similar to those "invincible/immortal while have contact with earth" monster/hero from different works. Does this mean soul in this work is a dense gas that can't float? I wonder if that means anything with the whole Egyptian death god thing going on (soul/heart heavier then feather motif into a skill later?).
Or it's just a random info they create to justify killing the immortal being and I'm overthinking it.