A natural condition caused by darkness that lets the animals who got stuck in the Dark Halls by mistake adapt to this world.
When a Hall grows too much, it turns into a realm of its own, with its own geography, fauna and flora, and even rules.
Robotic homunculi that serve both as mobile streetlamps and a system that assesses and warns about the dangers in the area.
Those who decide to gather resources from the Halls, depriving others from retrieving what they had lost. Some of them resort to kidnapping others to maximize their harvests.
Monsters of the Junkyard that can swim in its walls and floor. The only part of their bodies that has ever been seen is their arms they use to pull someone into the garbage.
Mouth-like structures created by the Red Sea to communicate with those it cannot absorb with a mere touch.