I think it would create shock in the scientific community, and institutions that are created around the scientific community, but it wouldn't create culture shock.

If moss was found on some exoplanet for instance, the scientific community would be very excited. Meanwhile, most (I'm guessing here obviously) people wouldn't realize how big of a deal that is, or might wonder "why we spend so much money to find moss". That's not a judgement on anybody, but I do think a lot of people would fall into that category. I think it would be the same if we detected breathable air.

If you want culture shock, you'll have find and invite a little green man aboard the ISS and somehow convince people that it's authentic.