The planet Calufrax was one of the victims of the Pirate Planet which materialised around Calufrax and sucked out all energy and life, leaving it condensed to the size of an Earth football.

The planet Calufrax was the second part of the Key to Time. The fourth Doctor and Romana were prevented from materialising on the planet by the Pirate Planet as it was attempting to materialise around it. They managed to get hold of the planet in it's condensed form and obtain the second segment of the Key To Time.

Adventures featuring Calufrax