This item would be one of a few things that are random from a list of what they find. Yes could move them to other planets with a extractor but only 2 on a planet of any of them same or different.

Crypt size 1 artifact +2 -20 population
Ruins size 1 artifact +2
Labyrinth size 1 artifact +3
Alien Station size 1 artifact +2 research +2
Ancient temple size 1 artifact +3
Dyson makers relic size 1 artifact +4 +1 research +100 planet defense.
Lost city random name size 1 artifact +5 +50 population can either be just lost city or a random name like the planets have.

Could use other ideas and modifiers if people have any including possible the cost and what items to make it. Could maybe cost ship-bots for digging or something.