Breath

The average orifice isn’t terribly busy; it’s a pair of lungs waiting for a probe or a pipe to poke in. It’s an exchange, a semi-recognizable interface for fire to move through its occasionally closed circuit. The opening is usually gated or shielded, plugged up with something or kept closed until coupling. But we still need to know where to put things in, so the inlets have evolved to stay puffed and prone. They invite use with arrows, lights and lipstick — marking entrances and exits. Some work harder than others:

The sparkplug fills the otherwise open head with light and leaves its fragile tip poking out of the cavity. The manifold butts up to exhaust ports that carry spent gases to a platinum hive. The lips part to take in oxygen and express carbon dioxide with each cycle, sucking in and pushing out something of the other. They expand, are satisfied and contract.