Shapechanger. The mimic can use its action to polymorph into a bed or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Adhesive (Object Form Only). The mimic adheres to anything that touches it. A creature adhered to the mimic is also grappled by it (escape DC 14). Ability checks made to escape this grapple have disadvantage.

False Appearance (Object Form Only). While the mimic remains motionless, it is indistinguishable from an ordinary bed.

Grappler. The mimic has advantage on attack rolls against any creature grappled by it.

Innate Spellcasting. The mimic's innate spellcasting ability is Wisdom (spell save DC 12). The mimic can innately cast the following spells, requiring no material components:

3/day each: sleep

Pseudopod. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) piercing damage plus 9 (2d8) acid damage.

Swallow. The mimic makes one bite attack against a Medium or smaller creature it is grappling. If the attack hits, the target takes the bite's damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the mimic, and it takes 14 (4d6) acid damage at the start of each of the mimic's turns.  The mimic can have only one target swallowed at a time. If the mimic dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.