Quicksilver I think it was called. I think it was a plastic maze and you had a little ooze of mercury in it that you tried to get through the maze. I will have to google a bit.
Found a picture and a description at
http://tv.cream.org/extras/toys/index.html![](http://tv.cream.org/extras/toys/images/quicksilver.jpg)
Of all the toys in our list, this is the one we can guarantee they'll never bring back. The kid's-plaything equivalent of the CFC-coolant fridge or leaded-petrol engine, the Quicksilver maze was so-called because it contained a measured blob of everyone's favourite poisonous liquid metal, mercury. . . .