Fertilized eggs?

[Azangie]

We recently took in a five month old Cochin cockerel. He is doing very well with my girls and although I haven’t seen him mating with them, I suspect that he is because it looks like we are starting to get fertile eggs. He is such a sweet boy and has already taken charge of his flock. My question is...Is this a fertilized egg or is it just wishful thinking?

Oh my goodness he looks just like my Rex sweetest rooster ever