The proto-morphic lifeform was created by Morjanus to gain access to London's gas system. She installed it at Blackthorne Gasworks before using self-hypnosis to make herself believe she was Penny Chapman.
Three years later, the lifeform had full integrated to the system and so, Penny started to regain her true identity. The Eighth Doctor and Penny visited Blackthorne. Penny was able to access the room in which the lifeform was stored simply by touching the door, even though it was padlocked. She fully regained her memories and fought with the Doctor on the rooftop. The lifeform used the gas system to release Pyrodines into London.
The Doctor managed to escape from her and destroyed the lifeform by hitting it with a crowbar to which he had attached some bullets. With its destruction, the Pyrodines disappeared. (COMIC: The Curious Tale of Spring-Heeled Jack)