Sluggula

Sluggula are tiny yellow slugs from The Legend of Zelda: The Minish Cap. They can only be fought when Link has shrunk to their size. They are slow and can be defeated in one blow.

Quote from The Legend of Zelda: The Minish Cap Sluggula figurine:

"Appears in Minish dungeons. They drop from the ceiling unexpectedly. They are slow, so take your time, and defeat them one by one."

Trivia
An early beta version of Twilight Princess included what appears to have been a Sluggula, however this enemy was never included in the final version of the game. It may have been replaced by the torch slug.