Okay kiddo, let me explain what a small carbonaceous fossil is. Have you ever seen a fossil before? It's like a very old rock that used to be a living thing a long, long time ago. Well, a carbonaceous fossil is a special type of fossil that's made of carbon - a kind of element. This means it's a fossil that's made up of tiny little pieces of the element carbon.
Now, these fossils are called "small" because they're not very big. They're usually less than a millimeter in size - that's even smaller than a bee! And they're called "carbonaceous" because of that carbon stuff I mentioned earlier. These little fossils can come from all kinds of different things, like plants or tiny sea creatures.
Why are these fossils important? Well, scientists can study them to learn more about what life was like a long time ago. They can look at the shape and structure of the fossil to figure out what kind of creature it came from. They can even use special tools to study the carbon inside the fossil and figure out how old it is!
So, that's what a small carbonaceous fossil is! It might be tiny, but it can tell us a lot about the past.