Blue spots on egg shells

[JordanH]

We have a flock of 10 hens (2 Wellsummer, 2 Bard Plymouth, 2 Cuckoo Maran and 4 Easter Eggers) I'm used to the variations in pigment color and brown spots on the brown eggs, but we've been noticing some dark blue spots (like the color of human veins) on several of our easter eggers eggs. We've also noticed it a couple of times with the brown eggs from our other chickens. Any idea what these blue spots are and are the eggs still safe to eat?

 

[Love4zion]

Do you have pictures?

 

[aart]

Pics would help for sure.
I've seen some bluish spots due to excess bloom, which is different than coating pigment..