dangerous and repulsive

This crab can never sleep.  It's entire body has become a long-time nuclear waste warning message of spikes, intended to deter human intrusion of its internal nuclear waste repositories for at least 10,000 years.

Even when future humans have animorphed into large, totally sexy fox people who just howl at one another and fuck a lot and despite not being able to read or write they will understand nothing valued is here...

More information on Nuclear semiotics can be found here