Planet (The Ghost's Story)

The Seventh Doctor and Ace visited a planet that had beautiful gem-flowers. The planet had at least two moons.

The Doctor deduced from ruins on the planet that it had once been a human colony but the colonists had died out.

On the planet there was a kind of lichen that could kill. It killed off the colonists and made its way into the TARDIS. (PROSE: The Ghost's Story)