What is this, really?

I mean, they say the mcrib is back, but where did it go? And why did it go? Was there an issue with the fact that it looks like it has bones, but It doesn't? And what did they do, to bring it back that they're celebrating so whole heartedly about it? The ad says, its a tender pork patty. But I don't get the rib part?? Help? Is that like a chicken having no nugget?