Prickly Pineapples

 is an unlockable achievement for the Bloons TD 3 iPhone and iPod Touch game. All achievements are provided by an app called OpenFeint. You must have OpenFeint installed in order for any achievements to be available.

Info
This achievement is unlocked when you complete Round 50 after having only used Tack Towers and Pineapples throughout the entire game. It awards 50 points upon unlocking it.