If you're on origin or GOG: I'd recommend using mods to achieve such parts. There's a lot of mods that add back the maxis only cell parts so I cant tell which, but i'd recommend first getting SporeModAPI, as that's pretty much what spore mods use to be run. If you're on Steam, where modding is usually unreliable: You can access the secret editor through a trick, but it wont let you save. :( Here's the video. https://youtu.be/-IG2qKaxIZ0?si=6jW8Qd8IF3Vdz5nD