Aqueducts

Aqueducts are structures that Ancient Rythulians used to power their cities. They functions by directing cloth creatures - particularly Fish - through a channel in the middle. Now, they mostly channel sand, without powering anything.

Aqueducts also doubled as walkways and bridges. The Broken Bridge is made up of pieces of aqueduct.

Speculation
Like most of their technology, aqueducts likely killed the fish that were channeled through them.

Aqueducts could probably be compared to real-life power lines.