Drones

Drones are small off-road items that do not do anything when not controlled.

They are treated as mechanical towers in the game, but they can't be upgraded.

They need to be controlled by something to move and attack.

Drillbot $500
Can drill underground, making it immune to most attacks, and pop up from underground to hit a bloon and pop off 5 layers. It then stays for 3-7 seconds, popping off one layer of the first 5 bloons to touch it. 5 HP and speed of green bloon.

MineBot $100
Can kamikaze into a bloon. 2/2 bomb tower missile explosion. Speed of yellow.