[It all sounds out there to him, but then again, his explanations must sound ridiculous to her too. And since Korra is so adamant that it isn't magic, maybe he just missed something. Maybe. He's not a geneticist.]

Okay, so you use the energy that the planet has to make rocks move.

[Let it go, Tony. Fuzzy science.]

I'd like to introduce you to some people back home. They'd be amazed to hear that.

[The smile fades when they get back to his "accident".]

It was a long time ago. I got caught in an explosion. Careless mishap on my part. It took awhile, but I recovered. Improved, actually.

...And I wanted to keep improving.