TERMITE MOUND BUILDING

Stigmergic construction: pheromone-driven piling creates emergent arches and pillars from simple local rules
Stigmergy (Grassé, 1959)
Termites: if carrying dirt AND pheromone > drop_threshold → drop dirt, emit pheromone. If not carrying AND pheromone > pick_threshold AND there's dirt → maybe pick up dirt.

No central coordination. Pheromone gradient creates positive feedback → pillars form, then arches bridge between them.