Update:
I just candled them!
All 9 remaining had development but...one just didn't seem right.
They are 5 days away from hatch day. I had to do them today since I'm away for the weekend and I'm not back until Tuesday.
So here are some photos of the 8 eggs (some eggs may be posted twice, it's hard remembering them) that seemed fine to me, movement visible in all:
This is the egg I was unsure on, it didn't seem right? There was no visible movement, just had a couple of darker blob patches and when I turned the egg, the contents inside just kinda swirled around. Not like the others:
I cracked open the egg, there was no smell so it wasn't rotting or anything. There wasn't anything unusual inside the egg.
The yolk sac was still really big though and the embryo was about the size of two beans. It's head was kinda visible but it had no other defining features like legs or a beak.
From what I could see, it was either going to be a black Silkie or Cuckoo like it's mother. The egg I removed was marked A from my Cuckoo Silkie.
Her other egg also didn't develop correctly so either it's down to how hers were handled in the 'to be eaten tray' or she isn't the best chick producer.
I feel bad but I know something wasn't right with it and I couldn't risk it exploding in the incubator when I'm away.