Strange egg flat on two sides with uneven pigmentation?

[GroovyFarmer]

I just had a very odd egg laid by one of my chickens. It is flat on two opposite long sides, and in the middle of each flat side is a circle of pale brown, which contrasts with the darker brown of the rest of the egg. When I tap it with my fingernail, it sounds more metallic and hollow than my other eggs. Should I be concerned?

 

[oldhenlikesdogs]

Could be nothing but a glitch. If it continues often the cause is a slight respiratory infection or bronchitis. I have a young hen lay flat sided eggs for a few months before she straightened out. She never appeared sick or stressed. I usually don't eat odd eggs, they get fed back to my chickens.