Is the skin of all Marans white? No matter what coloring the feathers are? Ya, I definitely don't have Marans if thats the case. I'm thinking they're EE too. Excuse another dumb question, but do all EE have the ear tufts? My little dark one doesnt seem to have them. I heard also that only the BCM will produce the dark chocolate eggs, and all the rest will produce regular brown. Is this true?
Please excuse my late reply -- I actually had an "affair" to attend this evening. Doesn't happen very often but when it does -- I'm all in! (Had a GREAT time. Introduced a whole bunch of short humans to poultry. Doing my part ....

My understanding is, all Marans are supposed to have the same colour skin - white. No matter what colour feathers. And I agree, your little dark chick doesn't seem to have muffs. It is really hard to determine breed from chick colour alone. LOTS of factors play in.
There are a couple of breeds that produce dark eggs: Barnevelders, Welsummers, Langshans, for example, however, Marans are reputed to have the darkest brown eggs.