Tiny holes in upper ears

I THINK I read about this before but I cannot find the previous thread (if there was one). Our DS came home about 7 months ago. He has 2 tiny holes (perfect in size and in the exact same place) on the outside of his ears. Not his earlobes, but the cartilidge (at least I think that is what that part is called). What are these? Every time I take him to the pediatrician I forget to ask. You guys probably know more anyway!!! THANKS!!