"Well, around then, anyway," Jack said. Guessing that Ianto's 'what' had been about the coral, he then said, "The coral was a very young TARDIS, Ianto. She grew, and I trained her."
He really wasn't making much sense, Jack realised. "I've got my own time and space ship," he said, "and she used to be...that piece of coral that sat on my desk for all those years."