Before each boss shows up, a short message shows up for about 2-3 seconds, telling the player what that boss is about. In this case, it says: Grows When Shot.
The only thing is that this is not the final boss. This is the boss on level 70. Next one where you need to figure out the message meaning is on level 120, and there are even more bosses after that.
The only thing is that this is not the final boss. This is the boss on level 70. Next one where you need to figure out the message meaning is on level 120, and there are even more bosses after that.