As expected the shorter days and cold weather has triggered a shutdown for the ladies of the coop.
This time of year they usually go through a molt. As a part of that process they also stop laying eggs. Out of 8 chickens one is still laying, so we're getting an egg each day.
The eggs are coming out with a fancy end or tail, see pics below. These are calcium deposits. There are many reasons this can occur, from the chickens age, lack of day light (shorter days), temperature, etc.
No cause for alarm. The eggs are still good and edible, in fact they're delicious! We'll keep an eye an watch this but suspect it'll correct itself over time. Certainly makes for interesting egg shells.