She's 2.5-3 years old...maybe older. She's a old bag but I love her to bitsIt appears to me to be a failure to completely encase the egg with calcium while passing through the egg glad. How old is the hen who laid it? I see this with older hens and especially at the end of a yearly egg cycle just before molt.
I believe the calcium "roll" around the edge of the hole points to this rather than a beak or toe poke.