Not "how did it appear there", but "how to get rid of it in the most brutal way possible" is the question you should be asking. May I offer hanging it on the hook and beating it up like piñata?
I personally enjoy throwing them into the river, they can't swim even if they get up so they just float downstream and leave my render distance giving me a lot of time without worring about them, plus yeeting them into the river is funny :D
you misunderstand, I know they can walk, but please explain to me how did it get inside the server room if I checked it 2 minutes ago and it was empty, walking is one thing but teleporting through walls?
oh boy, I always thought they spawn outside the base and walk towards it (mostly because of the event that causes all of them to pile up near uniform, funnily enough that hasn’t happend on this save)