Yeah, I posted in that Marans thread and then backed out again when it got contentious (Marans people being contentious, who'da thunk it!) The main diff between the Marans color and the Ameraucana color is that the Marans egg color is laid onto the surface, while the Amer color is through the entire egg shell. Different chemicals are used by the chicken's body to put the color in/on. Hemoglobin for the dark brown, and I forget what for the Amer. In fact, you can scrape the brown of a Maran's egg off, while an Amer egg color is not-scrapable, since it goes all the way through the shell.