Mirror Life
An existential threat to our biosphere.
Life on Earth is chiral - we’re made of right handed DNA and left handed proteins. And by “we” I mean everything that’s alive.
We have come to the point where we can control the stuff of life well enough to make mirror image molecules, and simple mirror image organisms are not far behind.
The historic event that comes to mind first is the carboniferous age. The Earth went through a sixty million year period where no bacteria could digest lignin, which is why we have massive coal beds. A mirror bacteria getting loose could be similar, upending a set of relationships that have been the norm for hundreds of millions of years.
Most mirror image life will likely be at a disadvantage, but all it takes is ONE creature that outcompetes its normal chirality peers. Letting this genie out of the bottle is a one way trip, one I hope we have the wisdom to avoid.