You go and leave a balloon up in the upper atmosphere....to gather particles to examine later.
It comes down, and you do analysis of various things within the filter. So, you get down microscopic things....thinner than a hair, and you come to this little ball....made out of titanium with a biological material oozing out.
Man-made? They can't say that. This would have been way up in the upper atmosphere. Who goes around making titanium balls with an empty core....which you fill up with a biological material? So far, some British scientists and Nobel Prize winners have not been able to come up with much....except they don't think it was originated from the Earth....but they can't really prove that point.
Why pick titanium? Corrosion resistance. If you wanted to preserve something for awful long time....not just years or centuries.....but eons.....you'd use titanium.
So I come to my humble opinion. Let's say you were a fairly advanced race and knew of a thousand planets where life of some sort might survive.....but you assume that none exists there.....you might want to 'blast' the planet with a bucket of BB's.....titanium BB's.....loaded with various things that would evolve and plant themselves. Trees, shrubs, bacteria, grass, marijuana, peanuts, and so on. Whether they work or not....doesn't matter. And you wouldn't worry about long term development because you aren't thinking of a 1,000 years or 10,000, or even 100,000 years. You are thinking millions of years.
Unless someone comes up to prove it's only seven years old and has to be a Earth-made item.....it's pretty much going to result in everyone believing there's another intelligent life out there, and they have some type of agenda.
If you seed a thousand planets......you might want to eventually come out and check your success rate.
