[Jmenschenfresser]

It's the "Ally Mine."

Dunno, it's a cool trick, but what would you do with it. That is unless you wanted to seal off part of your empire from even yourself for enough turns to make it worth building and laying them.

Could be useful against pesky AI allies that won't stop sending colony ships into your territories. Perhaps they would be good over dedicated construction worlds that have no resupply facilitt. Ships are built and then they leave.

Just trying to think of a senario where I'd use such mines for more than just to snub my neighbor.