No, that's not some mutated animal, this is the Ninja Monkey, a Magic-class tower that was released in the initial release of Bloons TD 6. Ninja Monkey attacks at a moderately fast speed, throwing a shuriken. Ninjas deal 1 damage and hit up to 2 bloons per shuriken. If you want to be a ninja, your first task is to add BTD 6 Ninja Monkey Sticker.