Black Crystal Reactor is the centre of Nemesis.
The Black Crystal Reactor was built by Saphir, the reactor is the only place on Nemesis that opens to the outside. It's where Usagi and the other Senshi arrived on Nemesis. It is the prime executor of the Black Moon Clan's plan to change the history of Earth. It can create Droids. Though the system is still unclear the Black Moon Clan accelerate the plants fusion reactions by force.
The Silver Crystal makes the reactor malfunction.