Montgomery's position as the sprite elder grants him the responsibility of looking after the Spirit Crystals. Alongside this, he is also tasked with determining whether a person is of pure heart and is worthy of receiving a spirit crystal.
In Attack of the Saiyans chapter 13, "The Ultimate Technique! Power of the Spirit Bomb", Montgomery appears in front of Goku, Bubbles, and Gregory soon after Goku has defeated the soul of Raditz, who wanted a spirit crystal for the power it would supposedly grant. As a part of his training under King Kai, Goku receives a spirit crystal from Montgomery, after the sprite admits that they have no mystical purpose whatsoever. Instead, he says they are the mark of one who is of pure heart, and reveals to Goku that he has been capable of using the Spirit Bomb the whole time.