They are sometimes annoying if you only have a dart left, but mostly they are helpful as you can pop many other bloons with them.
These bloons are commonly called the "Flower bloon" because they have a flower on them. They look like classic Green Bloons with a flower symbol on their surfaces.
Bloom Bloon can be a tongue twister if you say it really fast several times in a row.
It spawns 7 Bloons, and thus holds the record for spawning the most Bloons. It is also 1 of the 3 bloons that spawn more than 4 another, the others being the Dark Dirigible Titan, which spawns 6 camo regen ceramics, and the MOAB (BSM2 only), which spawns 8 Mini MOABs.
Strangely, if a Bloom Bloon gets popped by a Bomb Bloon, it will only be counted as 1 bloon popped; due to spawning 7 more bloons, it should be counted as 8 bloons popped. This is probably because the Bloom Bloon did not have enough time to spawn bloons or the explosion negates the ability to spawn additional bloons. Or simply, because the Bloons in it are never visible, and just visible Bloons are counted. This also happens with Green and Pink Spawning Bloons.