I was browsing the wiki page for “Square root of 2” where I saw a picture of a clay tablet dated about 1700 BCE. Apparently it is a Babylonian approximation for the square root of 2. But really it is a square with some markings. How do researchers know that what they are looking at is significant?
Image is found here: https://commons.m.wikimedia.org/wiki/File:Ybc7289-bw.jpg#mw-jump-to-license