I can remember one short story where the explorer finds life - I think on the Venus surface, so an early story before we knew how hostile the surface is. and he leaves a poop bag there, not realizing that it would make the lifeform extinct, a unique lifeform, only known life on Venus. The lifeform penetrates it and eats the rich material, and that kills it. I don't think it is intelligent, just multicellular. But it is destroyed because it is the only remaining example of its species on the planet, and not destroyed by the microbes. As the explorer leaves the planet, he doesn't know that he has made this lifeform he just discovered extinct.
Does anyone know this story? (Answered, thanks!)