Sharingan+ Rinnegan = Juubi eyes
Ill let the pictures to the talking, I just edited them.
Picture of the demon behind madara with 4 sharingans, EMS.
Demon with 2 Sharingans and 2 Rinnegans, made it a a couple of months ago, asking what might happend if uchiha had implanted 2 rinnegan eyes instead of sharingans, and you see that thing on the forehead of that demon, looks like and third eye.
So I edited so it had the juubi eye.
Im not concluding anything, just want thought about why that demon has that ring, circle thing on his forehead, just a cool detail or something more mysteries?