Me again. I need to clarify: The chick that didn't survive died because it was generally weak and had an unclosed navel. Not because of the feather issue.
https://www.backyardchickens.com/threads/chick-down-defect.1501772/
It appears I only posted one photo at the time in that thread. Three chicks I hatched last year were hatched covered in weird black bead-like bumps where the down was supposed to be. The one I showed in the photo didn't survive...
Hi, I am back... This post reminded me of some chicks I hatched last year. They head what looked like hard black beads on their backs that flaked off as their feathers came in.
I will link the thread I posted about that tomorrow so you can see the pictures. No real answers about the anomaly...