User blog comment:Fibbie/Nitrome Twin Shot 2: BONUS/@comment-5926454-20121230170308

I found the answer: The Bonus box, better known as Bonus is a power up that can be obtained like any other power up. If the player touches it when it appears, the words "bonus" will appear at the bottom of the screen in rainbow letters. After the player completes the level, they will be transported to a bonus level, where they will have 20 seconds to grab all the coins they can.