I brought 16 eggs into the house candled them all and we have 12 now in a box. When we candled them each egg was solid mass inside. No idea how old these eggs are for 'due date'. One egg I wiped clean because it had a yellow little clump on it. Now the clump is back, what is it?? Any idea how old these eggs could be? I have lights hovering over the eggs for heat, water glass in the box and a wet cloth. I do have a thermometer and its steady at 99. But what is the yellow clump...yolk? is the chick pipping? I'm afraid its bad and will explode! Thanks in advance for any advice.