What is this ring on eggshell?

[my beautiful girls]

What is this ring from? It looks like blood up close. Another weird thing it was in the run, not the nesting box. Haven't had either of these scenarios before. Normal size.

 

[Eggcessive]

It doesn’t match that much with any of the following perfectly, maybe a broken and mended egg, but you may judge:
https://www.backyardchickens.com/articles/common-egg-quality-problems.65923/