Although the Universe is 13.8 billion years old, life took a lot longer to develop. Estimates say that life ‘happened’ up to 17 million years ago somewhere in the Universe, but only spread through the Earth 3 million years ago. There are various theories as to how life developed on Earth specifically. Some think that the random collisions of molecules that give rise to life happened independently on Earth, since it had favourable conditions. Others think that this may have occurred someplace else, deep in the vastness of space, and that those small living creatures were transported to Earth via a meteorite.
At the moment, there is no way to confirm which of these theories is correct. It was thought that analysing fossil records could show whether any meteorite that arrived at the time life started actually contained living organisms. But Earth is an active planet, and its continuous geological activity has pretty much erased all evidence of it. But scientists have thought of an alternative.
If 17 million years ago there were meteorites containing life roaming around the universe colliding with planets like the Earth, they could have hit the Moon, since they are so close together. And the great thing about this possibility is that it is actually verifiable. The Moon has a much calmer tectonic history, since it currently does not contain any lava in its center to wreck fossil records. But at the time life is thought to have spread on Earth, the Moon was covered in lava, which is more helpful than you imagine. Several experiments in the past have shown that complex organic molecules that made up early life are able to withstand the high temperatures in the lava, and may have actually been protected from radiation by being buried deep inside the hot liquid.
So now we only need to go on a mining expedition to the Moon to find any fossils that may give us the next clue as to when and how life started in this wonderful Solar System of ours.