When the contents are not that of a 'normal' egg then this has usually been caused by a bit of sloughed off material (often from an inflamed or irritated oviduct) having found its way into the reproductive tract, which will in turn stimulate the oviduct to produce albumen /'white' and form an eggshell around it. This 'rooster'egg' /"wind" egg will usually consist only of eggwhite, though on occasion you may see what appears to be a yolk-like substance at the core, around which the white and shell have formed. it is not and it will often be miscolored or apeared "cooked"...
I would not eat anything unless I was sure it is a proper yolk .