I had one last year. The egg sat on the bench for over two weeks- but then just as I was going top toss it- on a whim I out it in the bator- never expecting it to even start developing. It did- and the twins survived 27 days. Sadly the little guy in front near the airsac had his head downwards- the one behind was fine to pip, but the little one in front died since it couldnt breathe. It was sad to get them so far along only to loose them but it was still an incredible 27 days. These guys were good sized ducklings- and completely formed - and perfect- the back one had started absorbing the yolk and trying to hatch. The egg was plenty big enough for two ducklings- but if the front little guy had his head the other way- there was a very good chance they both would have survived.