Reading through all of those signs makes it clear that most people who come to HN for civilized discussion also enjoy the opposite end of the spectrum in a different context.
I also realized the pictogram's filename is aem-0023-explosive_material.png, so I wasn't _too_ far off with "exploding planet". With slightly larger versions of the pictograms in the chooser and a hover label I could do a decent job of choosing the right one for the situation.
https://observatory.db.erau.edu/generators/signs/output/2020...
My partner's coworker had this up in his office. They're in health and safety.