It has been suggested that the north-polar hexagon found on Saturn is an unusual Rossby wave. If this is to be the case, one must not only explain how a Rossby wave can be hexagonal in shape, albeit with curved corners, but also why it is hexagonal rather than in the form of some other polygon. It is likely that a spectrum of Rossby waves with different amplitudes and wavelengths resulting from the velocity profile of the hexagonal jet is responsible for its shape.
THE_ENIGMA_OF SATURNS NORTH_POLAR_HEXAGON-Rev 3
https://arxiv.org/pdf/1711.00338.pdf
Link for Saturn video (3rd slide):
https://www.youtube.com/watch?v=BBQ_rnkqtpk
THE ENIGMA OF SATURN’S NORTH-POLAR HEXAGON