Milkbats

Milkbats first appear in the Red Rising Saga as a terrifying subterranean predator in Dark Age, where their massive colonies and paralyzing spines make them a deadly environmental hazard in the deep caverns of Mercury. Their introduction expands the series' world-building by showcasing the lethal fauna that thrives in the hostile, lightless depths beneath the planet's surface. Though only detailed in a single book so far, their presence hints at the broader ecosystem challenges that future expeditions and battles may face.