While we're on the topic of nuclear pollution, "nuclear semiotics" is an interdisciplinary field of research focused on creating a "warning message intended to deter human intrusion at nuclear waste repositories in the far future, within or above the order of magnitude of 10,000 years."

While 10K is a few orders of magnitude greater than 500, I imagine the problems may be similar... if not more extreme.

Source: https://en.wikipedia.org/wiki/Long-time_nuclear_waste_warnin...