Okay, imagine that you are exploring a really old place with big rocks that have been standing there for thousands of years. These rocks are so big and heavy that it's hard to imagine how anyone could have moved them without machines.
Now imagine that some people, even before there were any smartphones or computers or even books, decided to leave their mark on these rocks. They didn't write words like we do, but they made pictures and symbols that meant something to them. We call these pictures and symbols megalithic graffiti.
Megalithic graffiti symbols are like secret codes that people from a very, very long time ago left on these rocks. They might have been messages, like "Hey, our tribe was here," or "Watch out for dangerous animals in this area." Or they might have been symbols of things that were important to them, like the sun, the moon, or different animals.
Some of the megalithic graffiti symbols are pretty easy to understand, because they look like things we are familiar with. For example, a circle with lines coming off of it might be a sun symbol. But other symbols are more mysterious, and we might never know exactly what they meant.
The cool thing about megalithic graffiti symbols is that they help us learn about our past and the people who lived before us. We can study these symbols and try to figure out what they meant to the people who made them. And when we do, it's like we're cracking a secret code that's been hidden for thousands of years.