The black mark on a few was only the size of a pea or bean, but there was 3 or 4 marks. After it was open an chilled it would turn blueish to gray. Bruise? I don't understand how they could have, But maybe.
I was processing my colored Range Broilers, an found a Black spot in the meat, right between the breast bone an rectum, right where you open them up. The spot is about the size of a silver Dollar on most of them. The fat right there is discolored too. This is the only place I have found any...