Tiny spherical egg!

[Hens1952]

I have eight hens and production has gone way down in the last two weeks - FRIGID temperature! Down from 7-8 eggs daily to 3-4 a surprise today: a perfectly round egg that is about 3/4 inch in diameter!! Ideas?

 

[ChickenCanoe]

That's known as a wind egg. Likely no yolk in it. Sometimes a piece of tissue sloughs off and it causes membrane and albumen to be produced and that gets an egg shell.
How old are your birds?
As long as nutrition is good, I wouldn't worry about it - unless it continues.
Usually, cold has little to do with production but rather day length.