Posadise was planet with two rings. From space, it was green and brown, with the two rings parallel to each other. The rings were made up of asteroids (at least one inhabited by small blue furry creatures) and debris swept up from the planets surface by the huge sandstorms.
The native Posadians took advantage of these sandstorms, taking shelter during them and allowing the storms to sweep through the cities, cleaning them of debris. For years, the Posadians relied on this feature of the weather to keep their planet clean until the extent of waste material building up in the rings around the planet became too great and posed a problem for the lifeforms that lived in the rings. Only when the Posadians received visitors and believed them to be an invading force did they take note of their irresponsible behaviour. (DWAM: A Mess of Trouble)