I saw this very unusual thing at my Asian market. I first thought it was some kind of jewelry, but it's actually a water chestnut. It looks for all the world like a bull's head with horns. The outer shell is very hard, and plastic feeling. The clerk said they're very good eaten roasted as a snack.
I apologize in advance for the website link, but it has a really good picture of these things, if you sroll down a ways. Just ignore the attempts at humor!