The ark bloon is the parent of the Anti-Slow bloon & Heavy Bloon. It cannot be slowed down or knocked back through any means except for stunning effects & tempest tornado respectevly. It also takes 10 hits & moves at the same speed as the Black Bloon. It can be identified due to it's resemblence with a mushroom.
According to the Keener Bloonopedia, it used to take the name "Drug Bloon" due to it's resemblence to a mushroom.