Older cats with missing teeth appreciate softer food. Offer your cat a good quality canned cat food once a day. Stay away from the cheap stuff as cats have very specific protein needs. Your vet can suggest a brand. The extra moisture in the food is good for the kidneys. If your cat can...
Calcium deposits from a defective shell gland or improper diet.
https://extension.uga.edu/publications/detail.html?number=C1255&title=a-dozen-egg-abnormalities-how-they-affect-egg-quality#:~:text=Irregularly%20shaped%20excess%20calcium%20deposits,on%20eggs%20of%20any%20color.