It is possibly a Delaware. I figured out they lay dark eggs. When you got eggs I don't think they were in my normal mix but sometimes my daughter collects eggs. She is 14 and fairly responsible but she might have gotten some of the pen's eggs mixed in especially since at that time we thought our only dark egg layers were the marans and marans mix. Now the Delawares are part of the mix. I'm sorry about that. Hope a consistent dark brown egg layer is ok with you. Or course I can't be sure as since they are all hybrid it is a surprise but the ones I've hatched are fairly consistent haven't hatched any Delaswares yet. The gray one is called 'blue' and will feather out a steel bluish gray. I just sold my feathered out blue one. The mom is a splash and she should lay a blue egg. I love the color. I noticed that when I first got chickens they were all black with some black and white. Then I got a few reds. Silly as it sounds I really enjoyed when my one Ameracauna hatched splash just for some different colors. Now I love the color on the Blue laced Red Wyandottes.
Did the solid black come out of a blue or tan egg. If it came from a tan egg then it is a girl the barred rocks are sex linked.
Looks like 3 easter eggers, 3 marans mix, 1 rock/Orph girl, in that picture. Though the black one can be an easter egger too as I have two black ameracauna's so if it came from a blue egg sex is in the air but would be an easter egger.