I went out to the run to coop the hens up for the night and out of the blue, one of the hens puffed up and dropped an egg right there in the run. The others dashed over and broke it open immediately. They are all about 18 weeks old, so I thought maybe just two of the five were laying. Now I'm wondering if they aren't laying, but then eating them immediately. I haven't provided them any oyster shells, so I will do that starting tomorrow. I've been collecting one or two a day, laid in the nesting boxes. I am hoping I can break them of eating the eggs. Is this a lost cause?