[ELI5] How do archaeologists know that what they found was an actual 1.3 million year old axe and not just a weird shaped rock?

Question

Prompted by this article [https://www.aljazeera.com/news/2021/7/28/archaeologists-in-morocco-announce-major-stone-age-find](https://www.aljazeera.com/news/2021/7/28/archaeologists-in-morocco-announce-major-stone-age-find)

In: Earth Science

Answer 1

We can [see](https://www.rawstory.com/media-library/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNzA3NzA0Mi9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYzMzg0MjM5Nn0.N-Ep8MclXVJ72-jIs2JMLKBX5UAVw8vKhR2JN85B8gQ/image.png?width=1200&height=660) that the rock has been broken, it has bits chipped off the sides. It’s also broken in a very specific way: roughly symmetrical, and in a way that gives it a double-bladed edge. A rather specific way for a rock to break if it was just by chance, and exactly the kind of breakage you would expect from an individual deliberately trying to make a cutting instrument of some kind.