Mea culpa, figured this one out. Somehow the Xi'Chung migrated onto this planet, I have a treaty allowing this with them and must have missed how they transferred 100M+ people onto my world in one turn. They breath methane and are breeding like insect on this planet. Actually they ARE insects. Not too shabby, got me a non-domed mineral-rich colony, too bad it's the only methane planet in my systems
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