I'm certain that there have been cases like this where reddish mold has been mistaken for flesh. This just happened not too long ago somewhere else, (a molded Host anyway, not the rest of the story).
I think at this point they could just break it up and pour it into the Sacrarium, but I don't know the official procedure.
I am glad they announced the results of the tests so quickly.
Thanks for your answer. A few years ago I read a book about Eucharistic Miracles by Joan Cruz. I know that such miracles do happen, especially in times when people need to be drawn back to the faith. So considering the times we live in I was quite willing to accept such a miracle occuring in Dallas. But since we have a natural explanation I will pray that God use even this pseudo Miracle to proclaim the Truth of our Faith.