I did the math for fun and a helium-filled ZOMG would have to be over 400 metres across (assuming a spherical shape, would be longer for a pointed blimp shape) to float and carry everything inside. Also assumed that a ZOMG layer (4000 health) is the thickness of 400 regular layers.
ZOMG 2 meters...... look how big it is in the game!!!!
Worst that can create a ZOMG in real life, but would not have the same resistance as the "ZOMG" true: http://www.fotosdomundo.com.br/fotos/hindenburg/explosao-hindenburg.jpg
That just gave me an idea for a tower! A tower that can set fire to bloons like the burny stuff mortar! And a 4th tier upgrade could allow it to set fire to blimps!
I already thought of that, its called the flamethrower and has limited fuel but the fuel regenerates. And ive thought of other stuff too including tier 5 upgrades for every tower.