They call this cake a geode cake. Geode is a small cavity in a rock that's lined with crystals or other mineral matter. Very cool!! I've DJed and Officiated many weddings and by cake time, most guests are in the WHOOOO-HOOOO party mode and/or too full to eat! Who cares, YOU are the bride after all and will do whatever it takes to make your dreams come true!
THIS was my dream cake!
Video courtesy: youtube.com / Photo courtesy: Michelle Taylor's iPhone