All the hens are at least 2 yeard old. I thought the black one is a Jersey Giant. The isa reds i had were a little larger but not much. Its going to be fun to see what i have when the chicks are full grown. You would Think i could keep track of 6 or 8 chickens but i really dont know where i got the one laying the green eggs. There was another just like it but found it dead in the coop one day.
Hmm, definitely a mystery! Sorry about the loss
as for it being a jersey giant, I thought australorp because of the green shine to the festhers which i dont think jersey giants usually have. Plus look at the leg color, slate/grey and it'd be australorp, yellow jersey giant plus JG are usually way bigger 
my Australorps are my biggest chickens or at least heaviest, my Barred Rock is close in size and maybe just broader than them, my Easter Eggers are next in size the surprisingly the Orpingtons are last and are the smallest ones but one is catching up