The above link is a picture of what you might be looking for. I have one in my arsonal. I always try the dumbbell first, then the above mentioned tool. If neither of them work I use my jigsaw or sawsall to to make vertical cuts at 3-9-12 o'clock positions in the old drain, then pry it out with a screwdriver. Be carefull so you dont cut thru any plumbing you don't wish to replace.