Board Thread:Questions and Answers/@comment-160.67.72.29-20140804104938/@comment-15575766-20140804212237

That's not stupid at all! I had that question when I first played Bloons TD Battles Mobile! The one with the monkey picture is Monkey Boost, which doubles all your towers' attack speeds for ten seconds. If you're also wondering about the one with the bloon picture, it makes your sent bloons faster.