Snap!
I had a hen sitting, but had a feeling others were adding eggs after she started to sit. Didn't have time to separate her out till a few days ago. Today She's got four chicks, and a heap of stone cold, abandoned eggs... And one had stated to hatch. I picked it up, pulled bit of chipped shell away, and could see it just about breathing!, so it's in incubator. Highly doubt it will live but who knows.