We found this on the beach in St. Augustine. It is used to make one of my favorite foods. What food is that?
This is a kind of algae called Irish Moss (Chondrus crispus), even though it is not moss, and it is found many other places besides Ireland. It is one of several kinds of red algae that are used to produce thickening agents that are used in making many different products, including my personal favorite, ice cream.