I have never heard of a blue egg layer laying a brown egg, especially such a dark egg.I have always been told that a hen won't change egg color. The shade of the color may vary but not from say a blue to a dark brown!
Have I been mis-informed??? I have never had it happen with any of my girls.
They just do not have the physical capibilities to do so.
Tinted layers (Like the EEs) can lay a pinkish egg one day and a greenish tinited egg the next day.
Marans lay such a dark egg though, and their egg colors usually fades as lay season goes on, and can be extremely dark in spring, but by fall they lay a light brown egg even speckled as they "run outta paint" by the end of lay season....

Sure Sudsy doesn't have a Maran in the bunch ??????????