Do a search on "Spore". That should turn up the Spore save folder.
I don't have Spore installed but usually saved games are found in one of the following locations and the name of the folder should indicate it's a game save folder:
*Home>Library>Application Support> Look for Game Folder
*Home>Library>Preferences> Look for Game Folder
*Home>Documents> Look for Game Folder
*Possibly in the Game Application folder itself. If the Spore application shows up as an icon instead of a folder, select the icon, Right Click or Control click to pull up a menu and select show contents.
As far as Time Machine, run Time Machine and use the Mac help pull down menu for info on excluding folders. I'm not sure if TM is running all the time or it is run on specific occasions? If it's the active program, "help" should offer TM help when you select it.