I've read about shelless eggs here and there so I was not shocked when I found one today... But now I'm wondering whether to worry or not. My 5 hens have just started laying in October. For a while I was getting up to 5 eggs a day. Slowly it has decreased to one day I still got 5 then the next day 4. Then about 3 a day. Yesterday only 2. Today again 2 ... One being the shelless egg. It had a membrane. I feed them layer crumbled and have started putting out scratch for colder weather. I used to give them oyster shells but I stopped because the didn't seem to need it. I was finding the eggs had a little of what looked like calcium deposits on the shells (not much) so I stopped oyster shells about a month ago and all has been fine. I tossed a little serving of shells in the coop today after finding the shelless egg. Guess I just need to wait and see if it keeps happening or if it was just a fluke. At this point of winter in just happy to be getting any amount of eggs and keeping my flock healthy of course.