A cathedral
with no architect,that cools itself.
Watch it assemble. Two hundred blind agents carry grains of laterite up a scent gradient — pick up here, set down where the pheromone is strong. No termite holds the plan, yet open flues rise, galleries thread between them, and a section of Macrotermes michaelseni stands grain by grain. Then the fungus combs warm, and the whole nest begins to breathe.
Three local rules. Nobody in charge.
Every builder on the mound runs the same tiny loop with no memory of the whole. Order is stigmergic — the work already done tells the next termite what to do. Structure is a side effect of the scent, not a goal anyone holds.
Pick up a grain
Where the soil is loose and the scent is faint, lift one pellet of laterite and carry it.
Set it down
Drop it where the scent runs strongest — beside a grain a neighbour just cemented. Pillars thicken into walls.
Follow the scent
Fresh cement pheromone diffuses and fades. Each deposit reinforces the last — a template of humidity and CO₂ steers where flues stay open.
Flues, galleries, a nest — none of it drawn.
Run the same three rules a few million times and a building appears in the section: vertical chimneys venting the deep nest, horizontal galleries lacing them together, a domed royal cell and the pale fungus combs that heat the whole organism. The mound above ground is scaffolding for the traffic of air.
The chimney network
Blind pillar-building leaves vertical shafts. Stack effect draws stale, warm air up and out through the porous cap.
Lateral corridors
Horizontal runs cross-connect the flues so pressure equalises and the traffic of gas keeps moving.
The domed vault
A single armoured chamber at the core. The one place the colony treats as fixed; everything else is negotiable.
The furnace
Termitomyces gardens digest wood and throw off heat — the metabolic engine the mound is built to ventilate.
The section, solved as a lung.
Toggle Convection and the air is no longer decoration. Heat from the combs sets up a temperature field through the pore-space; that field generates vorticity; we relax the stream-function until the flow is divergence-free. Warm air rises in the flues, cools at the porous shell, and sinks back — a closed current, solved on the galleries the agents happened to leave behind.