My second chicken to give us eggs laid her first today. It had a very thin brown rubbery membrane and had splat on the coop floor. At first I thought it was a weird poop but upon closer inspection could see what must have been the "shell" and a yellow yolk color in the slimy goop. I hurried and cleaned it up as the other chickens were looking it over and pecking at it when I found it. My Question is why is the shell like this? Her sister that has been laying an egg a day for the last 9 days (first eggs) have nice hard shells on them. Does this mean the second chicken that laid the rubber egg isn't getting enough minerals in her diet or is this just a fluke that has to do with it being her first egg? Poor girl keeps singing the egg song on and off and then going back to the nesting box to sit. I think she is very confused as to what just happened and has no egg to fawn over. Is this something I need to worry about or is this a common first egg laying thing? *Chickens Diet- All my girls have been on layer mash since 18 weeks old. They are now 21 weeks old. They do get to free range 2-8 hours a day depending on if I am working or not. They also get a lot of leftover scraps from the kitchen and garden. Thanks for any insight you can give me.