Egg colour??

[ChristieB]

Hey there! It’s been a while, question is can a hen change egg colour?
I think I’m going crazy as I just found a blue egg in the coop and I have no idea who laid it, I have 4 pullets, hatched December, second generation Araucana crosses (grandmother is lavender auracana) so all have the potential but I thought they were all laying as I’ve been getting 3-4 brown eggs a day for the past month. So was someone holding out on me and just laid her first egg or can they suddenly change their egg colour?
Photo of eggs collected today, (I didn’t collect yesterday little ones belong to a Pekin)

 

[meetthebubus]

They don't change color so I'd say it's a new layer

 

[fur-mum]

x2.
The egg color may fade slightly through the season, but it'll never change from brown to blue.