They exist in case we ever make contact
with an alien CIVILIZATION.
The Big Bang Theory Season 9, Episode 10
End of human CIVILIZATION.
Westworld Season 3, Episode 8
Rode them from Valyria
to build the greatest CIVILIZATION
Game of Thrones Season 1, Episode 4
could be evidence
of alien CIVILIZATION.
The Big Bang Theory Season 12, Episode 20
...that any space-faring CIVILIZATION
would have to possess is touch.
The Big Bang Theory Season 8, Episode 21