What were herostones, and why were they erected?

What materials were used to inscribe records during the Sangam Age?

Which food items were considered luxuries in the Sangam Age?

Read the following excerpt and answer the question that follows:

"The Sangam texts mention prominently only the ports of Musiri, Puhar (Kaveripattinam) and Korkai, the three great ports of the three great rulers of the timess."

(Source: https://www.du.ac.in/up/oads/new-web/04012023_Appendix-108.pdf)

Who founded Kaveripattinam, and why was it significant?