Are you going for just updating? If so, I’d leave it alone. Culturally it’s ubiquitous and doesn’t require changing.
If you’re thinking more along the lines of a save version of the whole “how do we ensure future people know nuclear waste resides within” then you’re gonna run into the same problems they do, symbols change meaning over time. But if I had to pick something that may be obvious to most people, my vote is a scribe and a pen. Most cultures have writing, most cultures with writing save information by writing it down. There are problems, obviously, but if you gotta pick one, that’s my vote until I hear a better suggestion.
And for what it’s worth, with the nuclear waste sitch, my vote first the atomic priesthood
Firstly, this is fantastic. Did you write it?
Secondly, it’s like the hidden, secret love child of Douglas Adams and Iain Banks’ culture series, that spent weekends with a coked out Terry Pratchett, and it’s one of the best things I’ve ever read