User blog:Nevenenkulus/The Green Barrier

The Green Barrier is the 2nd to last colored Barrier. It is special due to containing In Observatorio, with its property of containing an even number of them canceling other Obervatorios out. If a Green Barrier had an odd number of Observatorios (which all have the exact same history), there would be one which would not be cancelled out and would delete everything to be the biggest.