There are loads of cellular creatures that live inside ice, and as there is ice on mars, the possibility for life on Mars does exist, and then there are all the non cellular life forms to look for as well. Even if Mars is completely dead at the moment, that sill leaves open the question of it's fossil records being explored to see if life once existed there in the past. Last but not least, if there are other types of lifeforms in the universe, we might not even recognise them. For example there could be crystalline life which if we ever encountered we would probably be to busy making engagement rings and desk ornaments from, to recognise as life.
A large black obelisk, crashed flying saucer, alien footprint, Santa.
Regards - Mr P