For all of you claiming tobi = obito, i don't think u have read "manga 597 - Secret of space-time ninjutsu".
As it has not been uploaded on base. I've read it, and in there kakashi asks tobi where he found that right eye(to confirm that it's obito's eye).
Tobi clearly states that "It was during the past world war, the fight at Kanabi bridge".
And we all know that Tobi likes to collect sharingans. So basically, Tobi found obito's body and recovered that right eye of his which may not have been damaged by the crushing rock.
Oh and btw, there are lot of people here claiming that tobi only has right eye(sharingan), well please got to Tobi vs konan chapter to confirm that Tobi uses sharingan in both eyes.
Tobi (most probably) may be an uchiha, but he is for sure not obito.