A used mask treasure? Well if that's the case I am always finding treasure. I found a treasure on a common artificial wreck site in Florida. The mas was even useable after I scraped off two barnacles. I also found treasure in the form of a mask on the ladder at our local quarry. It didn't fit, but it looked like a brand new mask...in fact I think my wife uses that mask. I also have found some snorkeling gear on the beach while driving through the keys a few weeks ago. I ended up picking it up so it didn't get washed away and left it on a picnic table in hopes the owners came back.