Once when I bought some chicks for a broody hen, one of them was a cornish and she grew so fast it was bigger than the mama and she started being mama to the babies. It was really cute. I did not have to worry about the babies getting cold!
You probably got leggerns. I have some leggerns as well and they're about the same size as the RIR's. I wasn't supposed to get any Cronish x's.. I was supposed to get Dark Cornishs and they sent me these darn Cornish x's. Bah. Oh well.
I got some chicks from TS a few weeks ago. Being new to chickens I got some RIR, assorted pullets and my dh said here get 2 of these Cornish pullets too. Well I was going to post to see if some thing was wrong with the white one (black one seems normal) it looks just like the one FutureChickenMan posted. So the Cornish is not going lay eggs, right? what happens if we don't butcher and just let it be a yard pet??