What if the Elder son eyes were actually the sharigan? But the swirl effect was the MS? Or some type of EMS since those eyes originated from him in the first place. It would explain why the Uchiha tablets go into so much details about the Sharigan and how it advances. It will also explain why the sharigan can advance to the Rinnegan as well. It would also explain how Tobi(considering if he is truly the elder son) is probably able to use his S/T jutsu in which his eyes are always hidden when he does uses it. But one thing we know for certain is that the swirls from Tobi's S/T tech follows the same pattern as the Elder sons designed eyes. Madara and Hashirama both inherited their powers according to Tobi so would this really mean that the sharigan was really the eyes of the Elder son? If you think about it. The more you advance your sharigan then the more you can read from the tablet so it claims. Which means that who ever written the tablet designed it for the sharigan to read as a starter.
Maybe I am wrong but I was just thinking about it.
Maybe I am wrong but I was just thinking about it.