Lead Bloon

Lead bloons are unique bloons that were introduced in BTD2 and has been featured in every subsequent game since.

Children
Black bloon x2

Speed
This bloon moves as slow as a red bloon and a M.O.A.B in Bloons Tower Defense 4. However, despite the fact that it's slow, it's still faster than a B.F.B. In fact, the 2nd Slowest Bloon was a 3-way tie.

Immunity
This bloon is metal, so it can't be popped with anything sharp. Anything else (besides Super Monkey Laser Vision ) can pop it.

Trivia

 * When they are introduced, BTD2 announces you can no longer pass the game with only road spikes or dart monkeys.
 * The super monkey's laser vision cannot pop lead bloons even though they're not sharp.