Long ago I read about how there’s a giant fungus somewhere in the Midwest, maybe Michigan, that has “roots” that extend for miles and miles, so they based this partly on that, I suppose.
The real world can be pretty creepy too if you think about it.
I played the game, didn't know they made a show out of it.
The fungus is basically a souped up version of this r/l one... it takes over the brain/nervous system of ants to feed on and spread its spores over a wider area.
https://en.m.wikipedia.org/wiki/Ophiocordyceps_unilateralis