Clay

A hard, shapeable soil form, normally in a grey color. It is easier to mold when wet, but when baked, it receives a hard, glass-like strength. Don't let this "glass-like strength" fool you though. It's alsos got glass-like weaknesses. When hit, it shatters.

Friend 1: Why did you break my clay sculpture
Friend 2: It was an accident, I remade it for you
Friend 1: Oh ok. Thanks for being a good friend.
Friend 2: No problem, dude.