@MrsPramm - Well, it's certainly possible, but there is a big argument against it. The archaea are considered to be a fairly ancient life-form, after all, particularly if they evolved back when the Earth's surface was very different.
And they have never got beyond the one celled stage, whereas you only have to look outside to see what creatures with our cells have managed to do. That might be because we've got more area to play with, but I also think there are simply limitations if you've got a hostile environment. And the surface of Venus is much more hostile than anything we've got on Earth.