There is a hurricane at the North Pole of Saturn which is a perfect hexagon.
Saturn's moon Titan is the size of Earth. Scientists' couldn't observe it thoroughly because of its thick atmosphere. In 2005 a probe named Huygens landed in titan and we get a good look of Titan.
It was an astonishing moment. Titan has mountains, landscapes, shorelines, rivers and lakes. But the rivers and lakes are not made of water. It is created by methane. Methane can be found in earth as a gaseous form. But in Titan at -180o celsius it is a liquid. The methane evaporates and creates clouds which came down as rain and create rivers, streams and lakes.