Ghost (Wario Land 4)
From the Super Mario Wiki, the Mario encyclopedia
The ghost cannot be attacked or defeated by Wario, nor can it hurt Wario. It will attempt to steal any type of loose Coin on the ground, but will not steal Blue or Red Crystals or Diamonds that float in the air. When Wario has Keyzer, the ghost will steal it instead, locking all doors and laughing until Wario recovers it.
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