From the Super Mario Wiki
20-Point Star (originally parsed 20 Point Star) is a Special Item that Yoshi can collect in Super Mario World 2: Yoshi's Island, and its remake, Yoshi's Island: Super Mario Advance 3. It can be obtained by winning certain minigames, or Mini Battles. It is worth 20 Stars, giving him 20 more seconds for the Countdown Timer. There is also a weaker special item called a 10-Point Star.
Yoshi's Island: Super Mario Advance 3
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