The Heart of Moon

Andrew: When planning Moon's regions, I wanted hers to not feel redundant with Five Pebbles' regions.

Andrew: I see the Five Pebbles region as being designed around the theme of the brain.

Andrew: So I wanted Moon's regions to be thematically designed around the heart.

Andrew: It only feels fitting given their personalities, storylines, and motives.

Andrew: Much of Submerged Superstructure's water and pipe systems form a huge mechanical circulatory system.

Andrew: Slag build-up clogged Moon's arterial passageways and blocked circulation through her conduits,
leading to her collapse being caused by essentially the iterator equivalent of a heart attack.

Andrew: This all wraps up in Rivulet's climax of inserting the rarefaction
cell into her heart, to electrically resuscitate her like a defibrillator.