As she examined the wiring and technology beneath the controls of the TARDIS, Crystal began humming faintly. After a moment, she rolled over and stood. "Doctor, hand me your sonic screwdriver, won't you?"
"It's broken," he objected. "You wouldn't know how to use it anyway."
Nevertheless, he handed it to her. Smiling as she took it, she began to speak. "Doctor, when we first met, I was barely aware of my telepathic ability. As time moved forward and with a little exposure to the Shards, I began to discover more that I could do. Telekinesis is another trait. Even small things..."
She stared intently at the sonic screwdriver, as if learning from the device itself exactly what its correct form was. As she stared at it, the screwdriver's familiar whirring and the blue light sputtered to life again. Crystal smiled in satisfaction and switched it off, handing it back to the Doctor. He took it and stared at Crystal, more than a little puzzled.
"Telekinesis, huh?" he murmured. Then, a wide grin split his face. "Fantastic!"
Crystal chuckled. "It's just a matter of being able to see inside it," she said. "To see what's wrong with it... and to place it back where it belongs."
"Now let's find out a little more about you," the Doctor said, changing the screwdriver's setting and again moving to scan Crystal. With a puzzled frown, he held the device at the base of her neck, just above her spine.
"That's..." he began, a little flustered. "Well, that's just impossible."
"What's impossible?" Crystal demanded.
"That technology there," the Doctor answered. Spinning her around and staring into her eyes, he went on, "There's a little control mechanism... no, that's not the right word... weapon? No... Device is the best way... Crystal, you have this little device embedded in your spine... well, just above it actually. But the tech required to make it... it's not invented for another ten thousand years!"
"Wonderful," Crystal muttered. "Add it to the growing stack of impossibilities about me. Seal of Rassilon on my necklace, some sort of innate knowledge that the thought of you repairing your Chameleon Circuit is hilarious, and now future tech in my spine. Anything else to add, Doctor?"
"Yeah," he answered. "We still haven't come to a conclusion about you..." He halted abruptly. "Why is me repairing the Chameleon Circuit so funny?"
Crystal laughed again and shook her head. "I don't know," she admitted, still giggling. "It just is."
Shaking his head, the Doctor moved to scan Crystal again. But this time, she began pacing.
"Hold still, will you?" he demanded. Crystal ignored him, once even going so far as to take a feeble swipe at the sonic screwdriver.
"Not now, Doctor," she murmured. "I think I'm remembering something."
"Remembering what?" he demanded, suddenly intense. "What are you remembering?"
"Go fix your ship," she said faintly. "Let me worry about that..."
After one further failed attempt to scan her, the Doctor gave up and did as she'd ordered.