[Billy's grinning like a complete fool, utterly gleeful that Teddy obviously likes it. He swings their joined hands a little, glancing sidelong at Teddy, even with his face buried in his hair.]

No, nature is amazing. This stuff actually exists on Earth- it's called bioluminescent plankton. They're called dinoflagellates, I read about them; they've got this chemical inside them that glows when something moves the area they're in, like the waves. They're basically fireflies in the water. The ocean's already got tons of plankton, so all I had to was add a bit of magic, and...

[Well. The sight speaks for itself. He opens his mouth to keep going - he really can ramble on forever - so Teddy might want to shut him up.]