What is the circumstances of a dinner plate with a radius of 4.5 inches

Its in the national history museum and you can't se the original because its locked away in a vault 

Humans have survived and thrived in mexico city by using technology to create greater access to land. when the spanish conquered the aztec capital, tenochtitlan, in the 16th century, they built mexico city by draining the lakes and filling in the lake water to create more arable land for agriculture. this technique of land reclamation has continued to be fundamental to human civilization in mexico city. 

Do you have a picture for this problem?