One of the eggs that developed under my broody passed away before hatching. When I opened it up, the chick had no top to his head, only one eye was formed and a very small top beak. It had a grayish mass (brain??) at the top of his head and over where one eye should have been. The baby's body was fully formed. What would cause this to happen? I believe the baby died somewhere between 14-18 days. Was this a defect or deficiency of some sort in one of the parents? The roo was delaware, and the mother could have been black star, RIR, or delaware, not sure who it came from. Two other chicks from the same hatch died around 18 days, the yolk was not absorbed, but I did not notice any strange anomalies. I only have one chick from that hatch of four eggs, a delaware/aussie mix, I believe, and s/he seems do be doing very well.