Hi, first time poster here, in need of DIY plumbing help. I had to remove my toilet and snake the drain because water was seeping out of the base of the toilet (where toilet meets floor). My home was built in the 1950's. Good news: Clog was removed. Bad news: The flange wasn't anchored to the floor and it popped off when I pulled up the toilet. Also, my drain pipe is cast iron but there is a large concrete slab above the top of the drain pipe, so it's not flush with surface of floor. I also don't know where my drain pipe begins? Please see attached picture. What is the smooth area with the question mark by it? Is that the pipe? Or is that PVC that was attached to the top of the cast iron pipe? Should I just put a new flange in? Or does this picture indicate bigger problems? Any recommendations?