Attack on Titan: Shingeki no Kyojin

[DarthEnderX]

Not sure, but weren't there just as many transformations without the use of a metal object?
Or does Eren have a teeth out of iron.

I'd have to go back an look. But a lot of the time, I thought he was wearing his swords/maneuver gear.

Obviously though, this is some theory I came up with last season, and during the long gap between seasons, I thought this theory was something the show had actually confirmed. But since nobody else knows what I'm talking about, it obviously wasn't.

Did the spoon during Eren´s former transformation in S1 dissolve or was it there afterwards?

No. In fact, it was a point they specifically brought up that the spoon he was holding was completely uneffected by the heat and pressure of his transformation(ep.19@16:05).