Muddy Buddy

A Muddy Buddy is a purple creature in Super Mario World 2: Yoshi's Island, appearing exclusively once in Level 5-4, Sluggy The Unshaven's Fort. When it comes into contact with the Yoshi, it will stick to his feet, allowing him to safely traverse over spikes. Yoshi can stop riding it with a Ground Pound. Unlike Poochy, another rideable creature, Yoshi can control the Muddy Buddy. In the game's remake, Yoshi's Island: Super Mario Advance 3, it makes an additional appearance in Secret 2, Mystery of the Castle?.

Super Mario World 2: Yoshi's Island
''Once they stick to the soles of your feet, they'll have no trouble getting on the spikes. Jumping is also a good way to get a jump on them.''
 *  Official Nintendo Player's Guide: When Yoshi traipses over lethal spikes in Sluggy the Unshaven's Fort, this funky-looking fellow protects his feet.
 * Shogakukan guide:「ベトッと足の裏にくっついたら、トゲの上でもへつちゃら. ジャンプカもアツプする. 」