So cute, and I love those little squiggle-marks! Seeing that chick just makes me want more chicks even more desperetly than I already do!
Just a heads-up, Mystery Bird is probably a rooster, and I hope you are fine with that!.
I'm sure you are compeletly aware that many hatcheries that offer a free chick often give away a male chick, because it means one less rooster for them to deal with!.
If your lucky, and 'he's a hen, congrats! I hope your adventures in chicken-raising will be wonderful!