I may have gotten Spock's World
and My Enemy, My Ally
mixed up. Sorry.
Having Aliens as an in-universe work of fiction is what I meant, hence me saying "the same applies".
Also: Jem'Hadar turn invisible, are really
tough and live to fight. Naussicans look more like Predators, but they don't act like them at all (at least not the way Predators are depicted in the movies).
It's probably best this "in-universe universe" can stay closed for now