
It sounds like your coop could use a bit of organizing and control - mostly for your peace of mind and so you can more closely monitor the health of your laying fleet. Having nesting spots hidden and permitting them to lay just anywhere outdoors, isn't an entirely safe or wise practice.
You can retrain them to lay in nesting boxes you provide for that purpose inside the coop by restricting them for a week to the coop or closed pen, having only access to the coop for that period.
It's so much safer for them. Predators could easily hurt them while they're trying to lay an egg under a bush. And like this petrified and possibly putrified egg you just discovered, you have no idea when it was laid or by whom.
It's better to check on your nesting boxes a couple times a day so you can spot any problems as they arise. And if a layer is having problems with a bound-up egg, you'll be able to see clearly that she's spending too much time on the nest and take measures to alleviate her distress before it becomes life threatening.
And if you see a broken egg, you can clean it up before your hens develop a taste for eggs.