What is the rarest moon form?

Have you ever wondered about the diversity and rarity of moons in our vast universe? If so, you may be intrigued by the question, "What is the rarest moon form?" When we delve into the mysteries of celestial bodies, we discover that moons come in various shapes, sizes, and compositions. But among them, one particular type stands out as particularly elusive and exceptional. What makes this moon form so unique and why is it considered the rarest of all? Let's embark on a journey to uncover the answer to this fascinating astronomical question.