Click the green flag to switch costume and create a new spiral. When you're done playing around, check out the original project and try making your own remix. It is really fun - many costumes produce surprising patterns :)
Thanks to @Daffodil_alias_Daffo for the original project Sprite Spirals: https://scratch.mit.edu/projects/796852535 In this remix, I just added different costumes from the Scratch library and changed it so that you don't have to use the space key.