5. Hiroshima relics
Two identic time capsules were placed beneath the ground at the time of the Japan World Expo in 1970. One of them got uncovered in 2000, yet another is still kept underground and will remain there for the next 5,000 years. Both time capsules have a slinky, glass eyeballs and darkened fingernail of a Hiroshima nuclear explosion survivor.
Capsules have other items as well, mostly related to arts, natural and social sciences. The box that got opened in 2000 was put back and will be opened every 200 years for examination. Both boxes will be opened one last time in 6970. As the primary component of human nails is keratin, which is a matter that does not decompose, it should still be undamaged even 1000 years from now.