Newbie Over Here- Need Help With My First Coin

Your coin is definitely a "legionary denarius", not too dissimilar to the kind posted today by FVRIVS RVFVS - I can clearly see the ship on one side, and the legionary eagle standard on the other. I would tend to assume it to be genuine, simply on the basis that most fake-makers do a much better job of making their coins easier to identify.

As a genuine ancient Roman denarius, issued by someone famous (Marc Antony, of "Antony and Cleopatra" fame) it is certainly not worthless. It is also made of silver, so even melted down completely it would not be worthless. However, Marc Antony made denarii to commemorate each of the Roman Legions, and in this condition it is impossible to tell which specific legion is commemorated on your coin. As such, it will be worth less than a coin for which this information is extractable. A coin dealer specializing in ancients would probably sell you one like it for $20 or so.