Animated Chest

Extra-dimensional Stomach. When you give this monster an item to hold it swallows it. Retrieving an item from the Animated Chest requires it's action. the extra-dimensional stomach does not consume items unless the Animated Chest has not been feed in over one year, and it will consume organic matter first, followed by inorganic matter, followed by magical items, at a rate of 1 lb per week. The chest is able to consume anything given enough time, but it prefers hardwoods that look like its body.

The extra-dimensional can hold up to 300 pounds of material or 30 cubic feet.

Placing the Chest inside an extra-dimensional space created by a Bag of Holding or similar item instantly destroys both items and opens a gate to the Astral Plane. The gate originates where the one item was placed inside the other. Any creature within 10 feet of the gate is sucked through it and deposited in a random location on the Astral Plane. The gate then closes. The gate is one-way only and can't be reopened.

False Appearance. While the Chest is motionless it is indistinguishable from a standard chest, constructed of a dark hardwood banded with iron.

Bonded Construct. When this construct is awoken by a sentient being they must make a DC 12 Wisdom (Animal Handling) or Charisma (Persuasion) check. On a success the Animated Chest becomes bonded to the sentient being. Once bonded, the Chest knows its owners location at all times and will attempt to stay within 30 feet of them, unless instructed to do otherwise. It will only open for its bond mate. 

In combat, the Animated Chest shares your initiative count, but it takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take one of the actions in its stat block or the Dash, Disengage, Help, Hide, or Search action.

Provide Item. If the chest has the requested item, it will hand it to you. You may have the chest perform this action before you go. 

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 3d8 + 3 bludgeoning damage. 

Devouring Mouth. When attached by a ranged attack the Animated chest can use it's action to make a Dexterity (Slight of Hand) check. If it rolls higher than the amount of damage dealt the chest consumes the attack and stores any physical portion internally. In this case, it takes zero damage.