There are now TREASURE BOXES in the game. These are dropped randomly and VERY rarely by any monster in the game. Some monsters are slightly more likely to drop one, however. If the monster you kill has one, the treasure box will drop along with whatever normal loot the monster normally drops.... so don't worry about treasure boxes getting in the way of boss monster special loot.
The treasure boxes are locked, and will require the help of a Rogue to lockpick them open. Opening a treasure box costs a lockpick EVEN for premium rogues. Picking doors is still free for rogues.
For a rogue, opening the treasure is easy... just go somewhere, drop the box, click the box, and hit USE.
If you are something else, you will have to take a rogue with you somewhere private. When the rogue opens the box, ANYBODY can pick up the item... so you will have to make sure to open your secret treasures in private.
Right now, treasure boxes only have normal items, although most of those items can be sold for much platinum. However, I will start making special items, weapons, armor and other things that are ONLY available through treasure boxes in the future.