Shrunken Apples

I saw this idea last year and we never got around to doing it, but this year we were successful.  We used a couple of different apples and the kids made their own faces.  Greg made the one that looks human.  Over the last 2 weeks they have shrunken and wrinkled and now I can't wait to throw them out.  They stink a little and they are just gross to look at too closely.  Someone told me they use potatoes instead of apples.  Maybe next year we will try that.