If I have a French blue copper marans from the same line that lays the left egg, what color would the chick lay (if a hen) if mixed with the egg on the right?
A very dark brown or dark olive egg. Assuming that the olive egger has 1 allele for the blue shell, breeding a Marans rooster to the olive egger would produce hens that lay different shell colors, but similar cuticle pigment colors.