This is an interesting microphone technology that uses a crystal to create soundwaves. These will be most commonly used for recording acoustic guitars as they specialize in enhancing the sounds from acoustic instruments. Crystal microphones will be found saddle-mounted to the instrument, collecting sound from the strings.
Each of these microphones have their own purposes, which is what you should consider when you are choosing which microphones best meet your needs. So whether you are doing live shows, recording instruments, or recording just vocals, each require its own mic.