Its Alive!

I decided to start my sourdough bread. 3 hours ago I made the sponge and put it in my proof box. It was less than half this size. Look at them bubbles. Something is happening. Now I'm supposed to wait 12 to 24 hours till I make the dough. This is the 3d recipe I got from the King Arthur recipe site, the first 2 turned out perfect, in fact better than perfect but I did do something I rarely do, I followed the recipe.
I hope this thing don't grow into "The Blob" and swallow everything in its path. If it does you won't hear from me. If not I'll post again regardless of the outcome.