Knobbly bit on top of egg

[Mid Wales chicken keeper]

Rocky my black rock, 19 months old laid a lovely big pinkish brown egg today, usual colour for her, but it has a strange swirly bit on the bottom. Sorry no photo, but has anyone else had this.?

 

[nuthatched]

It's not unusual, it just happens sometimes.
https://www.backyardchickens.com/articles/common-egg-quality-problems.65923/

 

[Mid Wales chicken keeper]

Thanks Nuthatched