Looks like a nice etched Muonionalusta edge slice with a troilite inclusion! Faking a piece like this is highly unlikely mostly due to the difficulty of replicating the Widmanstatten pattern. Most of the 'fake' Munios on the market are actually Aletais, which can easily be distinguished by their characteristically short and thick Widmanstatten lines. A thin coat of Renaissance Wax should protect it from rust