Acorns are born looking like baby acorns that are small, green and have tiny cupules. When they start to grow they lose their cupules and they grow like a litte bulb that flowers have when they are almost ready for blooming. When they are almost done they grow their cupules again but the cupule turnes out to be a brown color. When the acorns are very old they change from being smooth to rough.Only when they are very old the rough part pushes itself into the cupule and you can see a little bit of the rough part.