I got this email off eBay that started these test. (I am not happy with 5 of the eggs being marked with a maker. Maker contaminants hatching eggs. Pencil should be the only thing used on eggs. I will try my best to hatch these, but I would like replacements for at least those 5 eggs that you contaminated from the start. I usually have good hatches from healthy eggs but yours are contaminated and thin shelled which is another sign of unhealthy eggs. I will not leave feedback until this is resolved. As of right now I am not a happy customer. }) so will talk to my family my nephew decided to do is own test. well being a boy he went all out. one egg is sharpie and one is dry eraser marker. Both hatched out great. one pic you can see there is no marker bleeding though the egg shell. Egg were but in a sportsman bator and 21 day later go to beautiful chicks. Named sharpie and easier.