Zeta Minor

"Here on Zeta Minor is the boundary between existence as you know it and the other universe which you just don't understand. From the beginning of time it has existed side by side with the known universe. Each is the antithesis of the other. You call it "nothing", a word to cover ignorance. And centuries ago scientists invented another word for it. "Antimatter", they called it. And you, by coming here, have crossed the boundary into that other universe to plunder it."

Zeta Minor was the farthest planet out in the known universe. It contained a link to another universe, a universe of anti-matter. Zeta Minor's surface contained a jungle-like terrain and was home to anti-matter creatures.

In the year 37 166 the Doctor and Sarah Jane Smith responded to a distress call from Zeta Minor, a space crew landed shortly after their arrival on the planet. (DW: Planet of Evil)