Sometimes if it's just a small amount of yolk, they can survive it. This looks a bit more than that and may include some intestines. This is caused by temperatures being too high either during incubation or in the hatcher. It can also be due to hot spots in the bator (common with still air units). I would run your thermometer a half a degree to a full degree cooler for your next hatch to hopefully keep this from happening again. I hope the rest are ok.