The health of the bloon core is the total RBE of the bloons around it. For example, with the Red Bloon Trio, red bloons have 1 RBE, so 1 RBE x 3 = 3 HP. For Green Bloon Trios, 3 RBE x 3 = 9 HP for the bloon core. These can be killed in 2 ways: The only MOAB-class bloons that this can happen to are MOABs, BFBs, and ZOMGs. MOAB trios first appear on round 70, BFB trios on round 120, and ZOMG trios on round 190.