Crowing hen, or rooster?

[Dashboardx]

I have two white 16 week old Bantam Cochins who resemble roosters and spend their time crowing. However, today I heard what sounded like a distressed chicken so I opened up my coup to find what I thought was a rooster in the nesting box laying an egg. While I know this an undeniable sign of her being female, she in no way resembles a hen:

This is her/him only a week ago, as well as a video of him/her crowing. As you can see the wattle and comb are very large and red, uncharacteristic of Cochin hens. I was wondering if hens could develop physical male characteristics? They were raised alongside a Leghorn rooster of the same age and developed these characteristics/started crowing well after the Leghorn, and I've heard of hens crowing in the company of a rooster, but never developing physical characteristics.

 

[donrae]

Did you actually see the egg exit this bird? I have roosters that hang out in the nest box from time to time, especially the younger guys.

 

[Dashboardx]

I'm almost positive I did, yes. And we've been getting bantam sized eggs although we thought all three of our bantams were roosters.

 

[FVRM]

maybe it's another bantam? cause this one looks like 100% roo