[hh3k0]

> That's a frustrating response, because you must surely understand as a whole what they are saying.

It's late and I couldn't come up with something that'd survive the timespan in question, so I just wanted an example.

[holoduke]

Carbon ceramic brake discs from supercars will likely to survive a few billion years.

[andrewinardeer]

Surely plate tectonics after a few billion years would move these disc brakes down into the Earth's mantle and melt them?

[nemo]

We have fossils that are > 3 billion years old. While subduction does steadily erase the past, not everything subducts. See: https://en.wikipedia.org/wiki/Craton

[thfuran]

That depends where you leave them.

[almostnormal]

Mirror on the moon.

[saalweachter]

Hmmm, assuming there were an extra retro reflector on the moon, have we pointed a laser at enough of the moon to find it? At what rate would it acquire dust without wind?