We don't know if you have to use rinnegan or not to use it.... Because Madara probably used the limbo to survive the fight against hashirama.... and nagato didn't have any limboUsing the power of the Rinnegan, the user projects an undetectable shadow of themselves into the invisible world known as Rinbo
Nobody apart from Naruto and Sasuke can harm it because they both have the power of the Sage of 6 Paths and they both can sense and see it respectively