time capsule

/T AY1 M K AE1 P S AH0 L/
noun
  1. 1

    A sealed container, buried at some location, that contains records of contemporary life - to be rediscovered in the distant future.

  2. 2

    Something reflecting an historical setting by its nature, existing out of time due to isolation or some specific external influence.

Source: https://en.wiktionary.org/wiki/time%20capsule