Mimosa 3 was a sentient planet inhabited by Immunoglobulins.
It was attacked by macro-viruses. After a massive defeat, an Immunoglobulin general fled and went to 17th century Earth, where it became known as Healer. The Tenth Doctor helped it regain its confidence, allowing it to reproduce again. He took the new Immunoglobulin army back to Mimosa 3 in the TARDIS so they could fight and reclaim their planet. (COMIC: Black Death White Life)