Super Egg!

I found an egg in the chicken coop on Saturday.  Here is a photo.  The egg was big and heavy.  It was bigger than a clothes pin but smaller than a bread box.  The shell felt thin and when I moved it around I felt like there was something heavy inside.   I opened the egg on Sunday. Inside I found a yolk, some egg white, and another whole egg with shell included.  It reminded me of Russian nesting dolls.  The inside egg was normal in size.  I opened that egg and found a single yolk and egg white.  At first I wondered if the egg was safe to eat.  I knew the egg inside the small shell would be good to eat but what about the egg outside the inner shell?  I figured both eggs were probably in the ovary when the outer shell was formed so both should be good to eat.  I made French toast.  The giant egg tasted fine.  I know it was Phyllis or Kelly who constructed this unusual egg.  I observed them both.  They walked normally and acted normally so I guess they are okay.