While yes, conditions are incredibly harsh, we've found life in such a variety of places on Earth I can't imagine there's absolutely nothing here that couldn't

While yes, conditions are incredibly harsh, we've found life in such a variety of places on Earth I can't imagine there's absolutely nothing here that couldn't survive there - it's just it probably didn't hitch the ride to Mars. We've found bacteria(alive!) deep in polar ice, miles under the ground, on radioactive waste and in geothermal vents with no oxygen and in hundreds degrees celcius.