Just Got The Augustus We All Talked About. I Have Questions

It looks genuine to me. It was probably found after being in the ground for a long time and developed some dark toning and some surface roughness. With silver shipwreck coins there can be a lot of sea salt corrosion/porosity on them.

I would not try to drop an ancient coin to listen to the ping sound. Ancient silver coins can be porous not only on outside but all through the coin making them brittle. I accidentally dropped a Tiberius silver denarius on kitchen floor years ago and a piece broke off. It's porous inside. I glued the piece back on, It ruined it's value probably by half or more.

I was so upset I dropped it I got another one with better metal, good surfaces.