Today, I was making a pot of soup using some cheap steel pots that came with my rental apartment. I have no idea what brand they are but each has a lining on the outer bottom of the pot. After I poured some of the soup from a smaller pot into the larger one, I noticed a light powder on the surface of my soup. I first thought it was stray coriander but when I began to wash my smaller pot, I noticed that its bottom layer was loosening and a gritty, flaky substance was coming out of the crack. Does anyone know what this substance is? I skimmed the surface of the soup with a spoon to try and remove the debris but should I throw it away instead?