The Imaginary Bloon is exactly what its name suggests - an imaginary bloon. It looks exactly like a red bloon, but cannot be destroyed (with one exception) and does not take any lives when it escapes. However, your towers will still target it as though it is a real bloon (but their attacks just go right through it). If other bloons are coming at the same time as the Imaginary Bloon, but your towers are targeting it, you must recognize that the bloon is imaginary and change their targeting styles so that they will stop targeting it (otherwise, they will keep attacking it instead of the real bloons). The only thing that can destroy it is an Imaginary Friend, but you do not get any money when it is destroyed.