Just in case you have not been following @jerome’s work on vertex updating for SPS in the Feature requests section you should check out some of the PGs he produced
https://www.babylonjs-playground.com/#JKRLKH#4 to #44
also
https://www.babylonjs-playground.com/#WVQV0M to #5
thank you @JohnK
For your information, from the https://www.babylonjs-playground.com/#JKRLKH#17 , the shape is still a sphere that is morphed by displacing its vertices with some simple trigonometric combinations.
The https://www.babylonjs-playground.com/#WVQV0M#1 series are from an initial @JohnK’s idea