Extreme life: Oldest living thing.

As far as insanely long lived organisms go, there are plenty of good contenders. In fact, it's kind of difficult to call - Lobsters, for example, don't age.

They just die when we want to eat them.

And there are a surprising number of things that can live for really stupid amounts of time, especially amongst plants.  For example, this humble Mediterranean Seagrass.....

You think you know what boredom is? This seagrass has been growing in the same spot for maybe two hundred thousand years. If it could talk.... then this plant would be shrieking and gibbering like a man caught in the path of an avalanche with his junk frozen to a big rock.

......which is at least a hundred thousand years old, and maybe as old as two hundred thousand.

But if you really want to go for something surviving out of deep time, you want to go microscopic. The rule of thumb, you see, is that the simpler an organism is the more able it is to hibernate for insane lengths of time.

And, at a conservative guess, this microorganism is four hundred thousand years old......