Mimics are very heavy creatures for their size. The average mimic weighs from 500lb. Weight calculator roll 2 D100's +300lb

With the new rules of character creation, choose one ability score to increase by 2, and a different ability score by 1

Mimics are born already mature, and live just as long as humans.

Your are an Awakened Mimic, few if any of your kind have come before you. You are not restricted to any alignment due to your race. Only your experiences since your awakening effect your alignment. 

Mimics can take a variety of forms and sizes. Your default size is Medium, though you can become either Medium or Small depending on your current form.

Your base walking speed is 30 feet when in the form of a humanoid. When you are polymorphed into an object, or in your amorphous form your movement speed is 15.

You have thick tough skin that acts as a natural armor. When you aren’t wearing armor, your AC is 12 + your Constitution modifier. You can use your natural armor to determine your AC if the armor you wear would leave you with a lower AC. A shield’s benefits apply as normal while you use your natural armor.

You can speak, read, and write Common and one other language of your choice.

You are proficient in the Stealth skill.

You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

You have grown to have natural immunity to acid.

The mimic adheres to anything that touches it or that it touches that it chooses to adhere to. A Huge or smaller creature adhered to the mimic is also grappled by it.  Ability checks made to escape this grapple have disadvantage.  You have advantage on attack rolls against creatures you are grappling.

You can use your action to polymorph into an object, or into a humanoid form. You can do this the same amount of times per day as your proficiency bonus. You can always use an action to turn back into your amorphous form. Your statistics are the same in each form.

Any equipment you are wearing or carrying isn't transformed, it either drops to the floor or is stored within your body, if there is space.

You revert to your amorphous form if taken to 0hp, or killed. 

You can shapeshift into any object or humanoid once you've had at least 8 hours to study it/them, or during a long rest. The objects you turn into can be any object that is as big as a 5' cube. Anything bigger, like a door, can be as wide and tall as 10' but can be no thicker then 2'. 

The humanoid form you change into will be identical to how they were when you spent time studying them. If they were clothed, you will be them with those cloths on, the clothes will be apart of you and wont be able to be taken off. 

Mass is conserved, for example: a 200lb mimic transformed into a feather pillow still weighs 200lbs. 

Wile in amorphous or object for you are immune to the prone condition.