Does anyone have any idea what this is? It's like a hole but is solid like sand or gravel. It feels granular but is clearly an indentation. It was laid sometime today in the nest box, so it's not old. There's no leaking or anything.
In the process of creating an egg, the last stage is in the shell glad where the calcium is laid down over the membrane for the shell. That tip is the very last to close and create a complete shell. Sometimes the calcium either isn't adequate or for some reason is deposited in granular "beads", resulting in a rough deposit on the shell.
I have a hen who lays eggs with the tip completely covered with those bumps. Occasionally, an egg will have a real hole where the shell failed to be completely closed over the membrane. This is just how her eggs come out. She also has trouble with thin-shelled eggs, and it's probably because her body isn't utilizing calcium very well. You can provide extra calcium to hens like mine, but it won't necessarily help the problem.