Thin iron/steel sheets.

[Damianus Albus]

Not at all. They had to use something to produce strips. Rolling mills? Maybe, we don't know for sure. But whatever it was, it was able to produce strips on a big scale with constant thickness. Segmantata wasnt brought by aliens, romans had done them themself. How? I don't know, probably no one knows. We can only assume, think and talk about it. But out of the question is a fact they they had used something to produce them.

And my justification for musculata is not rolling mill. My justification for musculata are reliefs, economy, battle usage, recycling. This is what Im basing on, not rolling mills.

Rolling mills are only one way to make them.