Here's a quick one (27 min in total);

In Germany, this is called an: Eierschalensollbruchstellenverursacher.
Can you guess what it does?
Here's the correct pronunciation and use: https://www.youtube.com/watch?v=Fd7uhYXCBqY
I studied a little in school, long long ago. What I remember is that you need to separate all the parts that are stuck together.