- You may be looking for the god Moloch.
The exterior of the moon was grey and fractured. Where the Bridge met the moon was a smaller version of Belial's Pit, leading to the interior. Moloch was hollow and inside of it was vegetation and an artificial sun. This vegetation was once an Angel and was the feedback mechanism for the system, which worked together to modify morphic fields.
In 2157, when IMC came to claim the mining rights of the system, they killed all personnel on Moloch Base and burned down the vegetation within. The latter destroyed the feedback mechanism, so Alex Bannen was unable to fully control the morphic fields when he tampered with the controls on Belial. The Seventh Doctor, Bernice Summerfield, and Ace were able to bring the morphic fields back under control, and Alex and his son Mark became the vegetation within Moloch.