Crystals are often viewed as some of the most perfect natural formations on earth, but they do have their defects. In fact, there are many ways in which crystals can have defects with all of them being depended on the molecule substructure during formation.
YouTuber Steve Mould wanted to create a way to easily demonstrate crystal defects, so he created a plexiglass case and filled it with nearly 1000 ball bearings. As it turns out, utilizing ball bearings or balls of any sort, you can perfectly model nearly every kind of crystal defect.
The video below demonstrates in great detail how many crystal defects work whether they be holes or faults. The video is close to 15 minutes long, but you will come out the other side with a great admiration and understanding for crystal substructures.