Tubba Blubba's Heart
From the Super Mario Wiki
Tubba Blubba's Heart is, as the name implies, the heart of Tubba Blubba removed by Bowser and hidden in the Windy Mill. After having his heart removed Tubba Blubba became invincible, the heart controlling the body as if he is a puppet. However, Mario discovers Tubba Blubba's heart, and the two battle. It is the first half of Chapter 3's boss.
When the heart's HP reaches 5 or lower, it runs away from Mario and escapes the undergrounds of Windy Mill. When it reaches the surface, it sees Tubba Blubba outside and reunites with him. Tubba Blubba eats his heart and becomes vulnerable with his heart inside his body.
Tubba Blubba's Heart is seen in the parade after the player beats the final boss, chasing its body when three Boo carry Tubba Blubba away.
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