What is breakable like an egg?

Answer 1

I do hope this is not a riddle, because I'm offering a considered answer.

Molded or spun sugar would break very much like an egg, as would royal icing. All of these confections are used to create decorated Easter eggs, with brittle, fragile shells that can be broken very much like real eggs. This is sometimes put to nice effect, when little treats are hidden inside.

Beyond foodstuffs, very fine, thin porcelain is certainly breakable. I confess that I'm curious as to the direction of your question.