Sometimes a chest will refuse to open to the player.
There are 5 types of chests: Wooden, Bluesteel, Golden, Bandit's chest, and Spider Queen's chest. These items can vary from Mushcoins to potions to unique items that otherwise would've needed to be obtained through a premium currency called Ethyr. They can be opened by hitting them 5 times with your equipped weapon, and they give you items, but can only be opened once per save profile.
Chests can be found everywhere in the world of Vesteria.