What you see above isn't a series of nested bowls--it's much cleverer.
Created by the French design firm 5.5 for avant-garde Spanish chocolatier ChocolatFactory, the domes are actually edible chocolate. Each one is made of differing percentages of cocoa bean. The outermost dome has the least cocoa content, at 60%, and the innermost dome has the highest cocoa content, at 99%. (The percentage is stamped into the nub atop each bell.) When you lift that last dome...
...you get 100% cocoa. That is, a cocoa bean:
5.5 also created a chocolat bar which tells you exactly how many calories are contained in each piece:
The third piece they created doubles as a novel measuring system. Four different flavors come in three different-sized slices. When you order a full disc of chocolate, you can choose exactly how much you want of each variety--so long as the total adds up to 100%.