Ivory Rock is a human colony world that has been annexed by the Tau Empire. It's surface is mostly covered with calm ammonia seas, with long chains of islands the only landmasses. It was slated to be a paradise world and the largest attraction in the Gulf after the fall of Ulyssia after the engineers on Prask managed to develop a filtration system and orbital elevator to refine the seas to salt water and jettison the by product into space. This never happened.
The Tau Empire is now using it as its staging point in the Gulf. They promptly forcibly removed the seas and had them sucked aboard massive merchant tankers, to take back to the Empire as a source of ammonia for science, and to make the environment on Ivory Rock less hostile. They also introduced atmosphere generators to turn the acidic air breathable.