since my setting demands a warning symbol like this, I've had this one kicking around inside my brain for about a year, alongside the transformation hazard. it's about time I made this!
this is a symbol to indicate a self-replication hazard, usually of a non-biological origin. ever-smaller circles budding off a central starting point evoke the similarities to replication of living cells. the three-fold symmetry follows with traditional abstract warning signs.
while the elements of, say, a nanobot swarm, may themselves be made of the same stuff as living things, there are key differences that normally prevent them from replicating without bound; just in case they go beyond those bounds, it's a good idea to have this warning handy! (also an autoclave. maybe some caustic cleaners for good measure.)
there's no standard warning color for this one, so I've produced versions in black lines and white lines, for maximum contrast on any background. dark mode and light mode users might see an apparently blank image for one of these. both are 1200 pixels wide, as is becoming a standard for me with these. (yes, there are SVG versions, too)
I'm sure the rest of you can think of some other users for it, so! much like other hazard symbols I produce, this one is released under CC-BY-NC*. that is, you can use it in anything non-commercial, just make sure I get credit for the symbol in some way! meanwhile, if you use it for something you're selling, that's also fine with credit, as long as you're using it in a larger work; don't sell the symbol by itself, or as the major point of the thing being sold. (thus the little asterisk)
hope you enjoy!