What is that children's toy?

I am trying to think of the name of this childrens toy that you often see in waiting rooms... its hard to explain but ill try my best... it is on a platform and it has this metal contraption on it and blocks are stringed on so you move them in all different directions... there are loops and turns.. it reminds me of a roller coaster.... i know im horrible at describing this.... but if you know what im talking about and you know know the name of it... if it has a name