I have 6 girls and 5 of them have been laying every day for the last three weeks (when they started laying). The 6th girl started laying just a couple of days ago. Yesterday I let them out of the coop to free range really early and I noticed I only collected 4 eggs yesterday (I thought perhaps there was a chance the other two laid in the garden somewhere but usually they always go back to the coop to lay, even if they are out free ranging). This morning I opened up at 6am and collected 3 eggs. I went back to let them out of the run to free range 3 hours later and when I went to collect the remaining eggs, there were two whole ones but what looked like a lot of wetness in the nest, on closer inspection I found little pieces of shell stuck to one of the eggs and then one of the girls came in and grabbed a bit of shell that had fell onto the floor and ate it. I have 4 nest boxes but for some reason they all use the same one, they are all identical so I don't know why they don't use the others. Could it be that they stepped on it and broke an egg, or is it something to do with 2 of them not laying yesterday? I feed them layer feed and also give them kitchen scraps every day, not huge amounts but a little bit for a treat. The shells on their eggs have been hard from the start and always perfect eggs. I'm very new to keeping chickens so any advice would be great thank you!