After 2.5 years and maybe a thousand eggs, one of my girls produced this. Looks like something meaty in the yolk and it's pretty red. I've seen blood spots before, but never a case where the albumen is discolored. This one is like the color of tea. I've done a five minute search and not been able to find any images from the internet of a bad yolk that looks quite like this. I don't have a rooster. The birds do free-range the yard. I give the birds fresh water daily. I don't use fertilizers on my lawn. I use cracked corn, dumar layer pellets, and vegetable scraps for the birds. There are no signs of injury in the coop, so I don't suspect cannabalism. In prior years I went without any artificial heat. This year, whenever the temp drops to single digits, I use 1 heat lamp. Aside from that, no artificial light. Any thoughts would be appreciated.