Metal plate beneath Linothorakes or Spolades

[immortal]

It would still be easier and cheaper to produce one or two undecorated and unpolished plates that could be placed at the front of a T&Y cuirass to protect the vital organs, than it would be to make an entire bell cuirass. The linen or leather would stop you having to polish or treat the metal, so it would be more practical on campaign.

As I said before, I doubt that every T&Y had it, just as not every one had scale protection. As everything would be hand made it is quite likely there were several 'styles' or methods of producing the cuirass.