Legged Mimic

When I noticed it, I was placed in a dungeon as a treasure box.
Yup. I don’t know what to say, because I really don’t know. When I was attacked by a human, I tried to flee in desperation, unknowingly I grew a leg. So now, what should I do !?
This is a story of a girl who has become a mimic, how she shakes the world with the power she acquired.