Treasure Chests in the Seiken Densetsu series are not always what they appear to be. Mimic Boxes and Ogre Chests can usually be found to have replaced a normal treasure chest, and upon opening them they will attack you. In FFA and LoM the boxes do not act like treasure chests, and instead act like normal monsters. Ogre Boxes and Kaiser boxes returned in the trap wheels for treasure chests in SwoM. In CoM random treasure chests would occasionally turn into one of four types of boxes, each one was weak to a single weapon type.
Mimics do little more than open and close their lid while jumping around. They appear identical to treasure chests in the game, save for their giant Sunglasses.
In SoM Mimic Boxes are classified as Plants.
Mimic Box / Mimic’n (J)
For some strange reason nearly every treasure chest found late in the game in SoM has feet and will try to run away from your character. This does not mean they are all Mimic Boxes though, real Mimic Boxes are actually very rare enemies. Very rarely they will replace a treasure chest so that when your character tries to pick it up they will be bitten. The Mimic boxes will attack a few times and then retreat and pretend to be a regular chest again. Like the Mimics in FFA these monsters wear giant sunglasses.
In SD3 Ogre Boxes are classified as a Plants.
Whenever your character hits a trap wheel from a treasure chest there is a chance you could find an Ogre Box inside. Ogre Boxes look like normal treasure chests with big eyes and a small cape. They will hop around and bite you for great amounts of damage. They are always the same level as you are.
Kaiser Mimics are dark blue versions of Ogre Boxes. They are found later in the game and are much stronger.
In LoM Polter Boxes are classified as Poltergeists.
Polter Box / Ogre Box (J)
Due to the battle system in LoM Polter Boxes cannot act like normal treasure chests. They bear very little resemblance to the normal chests in the game. They walk around and will kick at you with their large feet. Sometimes a cat will pop out of them and shoot a star at you. As pets Polter Boxes are one of the most useful allies, they increase the chances you have of getting rare items.