Down at the port, the giant cranes stand along the water. To most people they are machinery. In Terminal City they are the Probes, and they are not loading ships. They are listening to somewhere else.
Ships leave the harbour with questions. They come back with weather, objects, languages, sounds, rumours, materials and patterns nobody here has seen before, and the cranes lift it all ashore. Sometimes the cargo is only the box the information travelled in.
Without the Probes the city would only ever feed on itself. If you see a crane turned to face inland instead of the sea, it has learned something. What did you see?