Golden Roid
From Planetarion Wiki
There are a number of unique asteroids in the Universe that can only be held by one planet at a time. These golden roids are injected into the Universe at the start of the round. Then the roids can be stolen in combat by attacking fleets if they luckily manage to cap the special roid in question.
The special roids will give an advantage to their owner. For example 5% mining bonus. Universe Miscellaneous page shows who currently owns the roids. Mining page showing which (if any) of Special Roids you currently own.
(larged quoted from Kloopys initial post on these roids)