Roman silver baffles experts

[Imperial Dave]

https://www.bbc.co.uk/news/uk-england-norfolk-65044932

Answers on a postcard

[Erpingham]

Bit of a belt plate?

[Duncan Head]

That would have been my first guess, but I can't immediately find any close parallel to the style.

[Ian61]

A fragment of a longer strip could be one of a number of normal items perhaps simply a fragment of a bangle type bracelet.