What is the gelatin in marshmallows made of?

The gelatin in marshmallows is made from collagen, a protein found in the skin, bones, and connective tissues of animals. When collagen is heated, it breaks down into smaller molecules called peptides, which are then used to make gelatin. Gelatin is a colorless, odorless, and tasteless powder that is used as a gelling agent in a variety of foods, including marshmallows.