Mini-MOAB (BTDi)

Ever felt like MOABs are just too big?

Mini-MOABs are significantly smaller than MOABs, and have less health, but they move a lot faster. They originally appeared in the Bloons Super Monkey series, and have returned to Bloons Tower Defense i. They appear every 10 rounds on patrol as bosses, up until the MOAB's appearance on round 40, and are spawned as bloon shields by higher-class blimps and bosses. They usually come in groups of 4 or, later in the game, as long, constant streams.

There are 3 different types of Mini-MOABs:
 * The smallest and weakest are Nano-MOABs, which thought that it would be a good idea to only hold a bunch of Red Bloons. Bomb shooters can take them out without even trying. 4 of them appear on round 10, and they come later in constant streams of hundreds or more, usually with multiple special properties combined in nasty ways.
 * Next up are Micro-MOABs. Essentially, they are mediocre in every way possible. They've discovered the advantages of holding smaller bloons that are more resilient to different types of attacks, but are still easily taken out with low-level towers. 4 of them appear on round 20, and they are frequently spawned for use as cannon fodder by larger bloons.
 * Finally, there's the Mini-MOABs. These are tougher than their smaller counterparts and may actually present a problem to your defense. They have a significant health pool and carry several Brown Bloons, which aren't very nice by themselves, let alone carried halfway down the track by one of these. 4 of them appear on round 30, as well as over the next few rounds. They are spawned by larger bloons such as the M.D.G. and are often seen following up large rushes of slower bloons, such as Purple Bloons, to add to the chaos.

Strategies
Bomb Shooters.

Seriously. They offer widespread popping power and can also deal extra damage to MOAB-class bloons. Perfect for wiping out swarms of these. Cluster Maulers (x/3/3) is a particularly useful combination, dealing damage over a huge area, and blasting 10 layers of armor off MOABs.

If you don't like bomb shooters, then other area denial towers will work pretty well too. Spike-o-Pults can be very useful when facing large streams of them, especially on tracks with lots of straight paths. Their anti-MOAB upgrades will wipe out a lot of Mini-MOABs, unless they are shielded, in which case you're out of luck. Ice Monkeys are also very useful.

If all else fails, there's always the "Fire as many projectiles as possible" option. Lots of Super Monkeys should get the job done with their high DPS.

Overall, Mini-MOABs aren't meant to kill you, just to apply pressure so that stronger bloons can make their way through your defenses. It's them you should be worried about.