Shell less egg?

[Paraclete]

So I was out in my coop with the big girls when I found one of my old hens in one of the laying boxes, she jumps out and I find these.

I'm assuming that one on the left would be considered a shell less egg. Now I just started thinking she might be laying these eggs because I noticed that she had been getting a dirty bum a bit lately, now seeing her in the box with this egg kinda proves my assumption.
Anyways, I know oyster shells and egg shells are some of my options for her but wondering if this is normal for an older girl, I'd say about 4 years old.

 

[Alexis]

Yep, that happens. It's always startling to me to reach in to get eggs and land on something that's not solid. ha!
It could happen with any age, but go ahead and bump up that oyster shell and see if it helps!

 

[Paraclete]

I was more like "ahhhh so that's what it looks like" when I found the egg.

But yeah, already bought some shell and started my girls on the stuff, hope it helps. Lol and thanks for posting something, was thinking it slipped by everyone.