I'm not saying this to be non-scientific or conspiratorial or anything. This is actually very cool! And respectfully, I think a real xenobiologist can come up

I'm not saying this to be non-scientific or conspiratorial or anything. This is actually very cool! And respectfully, I think a real xenobiologist can come up with more creative ways to get spores from the ISM into the atmosphere. For instance maybe they come in on small meteorites, right? Maybe they come in around the modified heliosphere termination shock, as the earth swings through it. The turbulence in the boundary layer manages to decelerate the ICM so that components of it can drift into the atmosphere on low energy trajectories. Fun right? So to be clear if you were trying to reduce my anxiety here, that's not really what I'm feeling. I'm feeling wonder and creativity. I would prefer for you to brainstorm cute scientific mechanisms that might allow it to happen!