To carry on @BambooGarden’s proposal in the other thread. I like optical illusions because they demonstrate something instantly: the reality of the image is indisputably there, but the brain does not know what to make of it.
And it will be the same for Safe: my data is here whenever I need it, and yet I cannot comprehend what the autonomous network does to keep it safe, nor to reconstruct it from shattered pieces. But that’s ok, because privacy and security should be a “mindless” task, not something that each and everyone has to be wary of when interacting with a computer.
So… an hexagon + an impossible cube 
I also really like the proposal of @dyamanaka; maybe a play with perspective could make it the logo that will unite the community.