Excroth

Excroth, located in the Excroth system, was the "favo[u]rite planet" of the Ninth Doctor. He once took Rose Tyler and Jack Harkness there, but upon arrival found that the planet had been destroyed. At the time they arrived, the Doctor said should have been the middle of the Second Excrothian Tetrarchy, a period of unparalleled scientific enlightenment. The planet had been destroyed by a Dalek-made entropy engine, used by the Unon to prevent Excrothians from developing time travel. (COMIC: Weapons of Past Destruction)