[[WMG:An InexplicableTreasureChest is the cast off shell of a ChestMonster.]]
Which is why they're everywhere, and why nobody seems to have the job of making them. Some alterations for locks; and presto! Instant container. Pity it still looks like something trying to kill you.
* So Chests actually look like Mimics.
** In addition, mimic spores coalesce around items that adventures drop because their [[{{Inventory Management Puzzle}}inventory screen is full.]] If nobody comes around long enough for them to feed on, they die or cast off the shell and find a different spot; leaving a chest with a single item in it.

[[WMG: Alternatively, any InexplicableTreasureChest that doesn't kill you is simply a non-aggressive ChestMonster.]]
The "core" of the ChestMonster is actually the item inside. They use adventurers to spread their spores around; and reform their chest shell when they get dropped.
* They die if it's a single-use item, but this happens in nature all the time. As long as more are spread than are consumed, it works.