Monkey Helicarrier

Monkey Helicarrier is the special unit in Bloons Tower Defense 8 and Bloons Tower Defense 10. It has Infinite HP, as well as consisting of: In Bloons Tower Defense 8, there is a special mission called Operation Skyfall.
 * 6 Machine Gun Turrets
 * 4 Missile Launchers (On the wings)
 * 4 Plasma Cannons
 * 1 Guardian Cannon (Cockpit)

It was the Monkey Empire's Headquarters, which can fly and move it anywhere.

How to Unlock a Monkey Helicarrier as the special agent (Secret)

 * First, beat Conveyor S on Impoppable Difficulty.
 * Next, beat Operation Skyfall without losing any lives.
 * Last, there we have it: The Monkey Helicarrier is now the special agent.