Along your journey, you'll find various crystals that will enhance certain abilities. The crystals will, however, soon fade, crack, break, and finally crumble. When the crystals break completely, they will be removed from stock, and their powers will be gone. Keep an eye on your crystals. If it looks like it will break soon, highlight the certain crystal, select "DROP", and pick it back up. It will be renewed as if you never picked it up.