Inside a birds egg

I had an egg from last year and I found one under a tree down the back so I thought I could do something with those for a lazy Sunday blip.
Arranging them I managed to drop both on the floor and one revealed this tent affair inside. The other was in even more pieces. So here is what is inside the birds egg after drying for a year.
An awful lot of dust comes off them which I didn't see till now.