What do i have?

[HappyHippyChick]

How old are they? If the circled one here
View attachment 3737392
is the one in question, it’s a pullet.

I cannot really tell but the one that is circled appears there may be a clue regarding the tail feathers which could be the answer. The stance seems more cockerelish but maybe wait and see.

 

[NatJ]

They are all about 8 months old.

At 8 months old, that would almost certainly be female.

Considering the body shape and earlobe color, that should be an early-maturing type of chicken, which means a male would have been crowing months ago, and would also have grown unmistakable male-specific feathering by this time.

So if it is still a "maybe" at this age, that almost certainly means female.

I got a white egg just yesterday. It may be a different breed.

White egg sounds right for what that one probably is.

I bought 6 black majesty maran chicks. They were supposed to all be hens.

Are these the only chickens you have?

Marans should lay dark brown eggs. So if they are your only chickens, and you got a white egg, then one is definitely not a Marans (and the one most likely to be not-Marans is the one that looks different than the rest.)