Okay, so let's imagine that you are playing with some toys on the floor, like blocks and little figurines. Now, let's say that someone came in and put some special tiny particles on your toys that you can't see. These particles are called "clays."
Now, there's a really smart grown-up named Graham Cairns-Smith who thinks that maybe, a long time ago, something like this happened on Earth. He thinks that maybe there were certain chemicals in the water and in the environment that mixed with these clays, and together they started to form life!
It's kind of like how you might use your blocks to build a tower, and then maybe you add some figurines on top to make it more interesting. But with these chemicals and clays, it was even more complicated because they all had to fit together just right for life to start.
This idea is called "clay theory," and it's a really interesting idea that some scientists still think might be true. Basically, Graham Cairns-Smith looked at tiny things we can't see with our eyes, and thought really hard about how they might have come together to create something much bigger - like life on Earth!