Glad Torpedo Ted
From the Super Mario Wiki
Glad Torpedo Teds are water-based enemies in the game Super Princess Peach. They are Torpedo Teds affected by the glad vibes. Like all glad enemies, they have huge smiles and emit music notes, they are also golden in color. Somewhat more dangerous than their unemotional brethren, while they're swimming forward, they move up and down. As with all Torpedo Teds, they are invulnerable.