Regrowth Bloon

Regrowth Bloons (or Regenerating/Regen Bloons) are heart-shaped bloons that grow one extra layer each second, up to their original form (e.g. if a pink regrowth bloon is popped into a green regen bloon, it will only regenerate up to pink).

Regrowth Bloons can also have Camo status at the same time, making Camo Regrowths particularly dangerous. Regrowth Bloons can appear on any level of the bloons family line from Red Bloon to Ceramic, although MOAB-Class Bloons can't be Regrowth Bloons (nor their spawned children).

Strategy
Regrowth Bloons born in groups from their parents will also grow seperately and will not merge, meaning that a single Ceramic Regrowth Bloon can easily multiply into a large army. A good exaple of this would be a Black bloon being popped into 2 Pink Bloons, which regrow into 2 blacks, which each get popped into 2 pinks, and so on. Use something with force attack speed to take care of these.

Generally, it is best not to pop regrowth bloons that have multiple children/grandchildren/. Use Viral Frost early to stop them from multiplying too much.

Trivia

 * If you popped a regrowth bloon that just regrew its old layer, you won't get money for popping that layer. You only get money for popping the layer below the ones you popped.
 * If a Rainbow Regrowth (spawned from a Ceramic) regenerates, it will regenerate straight into the Ceramic (skipping the cracks).
 * Corrosive Glue acts faster than regeneration. However, it will take a while before the bloons is totally popped, because after Corrosive Glue kicks in, regrowth kicks in, and so is not recommended for popping regeneration bloons. However, Bloon Dissolver acts at almost triple the speed, so it's more effective.
 * In the Covert Pops Special Mission, bloons that are normally Camo become Regrowth as well.
 * If a Summon Whirlwind is placed near the end of a track, and 1 Black Regrowth Bloon (or any bloon that spawns 2 bloons when popped) in sandbox mode, bloons will keep appearing because when the Black Bloon is popped, it will spawn 2 bloons and while those bloons are being blown to the start they will turn to Black Bloons and this will continue and continue, making them a bad choice when it comes to popping regen bloons.
 * Beekeepers and Monkey Villages with the High Energy Beacon are good to pop Regrowth Bloons.