WHAT is THIS?
Lash eggs are fairly common in chickens who are internal layers or have salpingitis. Your hen may have had a blip in her shell gland that put a shell on a lash egg. A picture would really help. Here is a good article to read about lash eggs with pictures:
I keep trying to add the picture but it won't let me 😔 This dime size piece was separate from the rest of the eggs inside the shell. Yolk was pretty and yellow and full, separate from the white as it should be but when I cracked it, everything fell into the pan as normal and behind it fell out this meaty piece. I guess I'll just need to really keep an eye on her.
Yeah I would keep an eye on her. The double yolk is a bit worrisome too, especially for a leghorn. Double yolks also show a "glitch" in the reproductive system and supposedly hens that lay them frequently have more reproductive problems.
If that were my bird and was a pet I might think about a hormone implant to stop laying.
It also could have been a large meat spot. Here is an article about egg problems, and a couple of threads on how to upload a picture: