Check it yourself! Do an image search for treasure chest. Select a few good ones. You'll see to match with them you must insert:
- a lock
- edge and surface reinforcements
- material texture details
- a treasure, if your chest happens to be open
- lights, shadows and maybe some shine
- plausible colors.
As a practice job you can well try to copy the things. I do not mean copying and pasting, but drawing. It's useful for your learning. Remember to make fully your own version if you are going to give or show it to others.
The extrusion gave to you so little part of the needed things that as well you can draw the chest with the pen. I bet it's 500% more useful for your learning.
If you happen to wait for the missing things something as easy as the extruding is for the base chest body shape, you will miss it totally. You must draw them or copy clipart shapes.