When chickens lay such eggs, rural areas consider it a bad omen. In fact, it is because foreign objects such as shed mucosal tissue, small clots (due to follicle bleeding during ovulation), worms in the intestines (sometimes accidentally migrating upward and reaching the fallopian tube) fall into the fallopian tube and stimulate the protein production of the fallopian tube. The secretory department and the uterus secrete albumen and eggshells, which are wrapped around the foreign body, thus forming a yolkless egg without yolk. This is not a disease but just a coincidence.