If the eggs are too dry they will show dents in them at first and ultimately shrivel up. If you are using vermiculite in the container, the way most people on here get the moisture correct is to take a small amount after adding water to it and squeeze it in your hand. You should get a couple of drops out if the moistened vermiculite. If there are no drops, add water, it too many drops sqeeze out add some more vermiculite. It does not take too long for eggs to dry out. I have seen an egg laid on the bottom of the cage shrivel beyond saving in less than 8 hours.