I have mentioned how, or why they form...nobody really knows. Freaky genetics, unusual energetic vortices like a twisted tree, dunno!
But, they sure are cool and fascinating. There are many variations to saguaros, twisted arms, thin, thick, tall, arm positions on the main stalk, number of arms. They vary from region and locale. These cresteds, are everywhere and unique as one in ten thousand.
Jbee