What happened here?

[AKNan]

Can anyone tell me what happened with this egg my Easter Egger laid?
It has a membrane attached on the outside of the shell through a hole
of sorts. This hen is not feeling well right now either after this egg. She is
sitting around fluffed up. She is 7 months old and just started laying being
the last one of my flock of 8 to lay.

 

[justplainbatty]

Here are some sites that will explainhttps://www.google.com/search?q=chicken+laying+egg+with+membrane+on+outside&ie=utf-8&oe=utf-8
Hope this helps.