I have just collected eggs from one of my serama pens and discovered a broken egg with a very soft shell,the egg looked complete but was empty I gather it had broken because of the soft shell,I could crush the shell between my thumb and forefinger and it felt almost elasticy with soft brittle bits (only way I can describe it)The four hens in the pen have all laid before,3 of them in their second season and the other one about 7 months old.Diet has crossed my mind but I havnt altered it in any way for the past year and all the other eggs have been perfect Any answers please????