In other words, why don’t they have a flat “side” from sitting on a flat surface as the chocolate dries and hardens? I’ve been wondering this for years!
I’m new here… I’m so glad I found a place where I can post the questions I’ve wondered about for so long! I have so many! 
Good question. Im no expert on this (or anything for that matter) but I have a guess. If you’ve ever seen the process of making many chocolate covered candies then it would help. They use big tumblers that, well, tumble the candy, then the chocolate syrup is added while tumbling. The candy is tumbled until the chocolate hardens. Best thing I can come up with.
Here’s a link all about it: Panning nuts in chocolate.
Thanks guys!