This looks like an ordinary shoulder bag, however, it is the mouth of an interdimensional being, called Ooza'ark trapped into this object.
If the flap is opened, multiple rows of teeth are visible and a longue slithering tongue. Most likely, Ooza'ark will start trash talking, asking to be fed, passing insulting comment about any creature it senses within 30'.
If the flap is closed, Ooza'ark cannot talk and the bag will not move.
D&D 5th Edition Properties
A first time user will be grabbed by the slithering tongue. That person must succeed a DC 16 acrobatic or athletic roll or get bitten, suffering 3d6+4 piercing damage.
If fed anything non magical, it will destroy it. If fed something magical, it will regurgitate it with lots of bile and otherwise be non-functional for 1d6 days.
Anytime someone feeds it organic material, they benefit from the effect of the cantrip Guidance.
If fed something good, once per day Wooza'ark will function as a divination spell.
- Parts of a freshly slain foe: Augury.
- Something really delicious, like a living baby creature: Divination
- Something really rare, like fresh dragon organs: Contact Other Plane spell.