Salvo the Slime

Salvo the Slime is the boss of World 1 in the game Super Mario World 2: Yoshi's Island. Salvo jumps at the player, trying to push them into the lava pit, though unlike most enemies, the player is not hurt by Salvo's touch. However, Lemon Drops break off Salvo when he is hit. The more Salvo is hit, the smaller he gets, until he dissapears altogether.

Salvo makes an unexpected appearance as the boss on the second floor of the duel tower in Mario Party Advance, surprisingly this game shows he is capable of speech.

Trivia

 * Salvo is actually a transformed Lemon Drop, even though he resembles a giant Slime.
 * Gilbert the Gooey was probably inspired by Salvo.