Yes, reindeer moss is a common food source for reindeer. It's a type of lichen that grows in cold, arctic regions, and reindeer eat it for its nutrients and to help them survive in harsh winter conditions. Reindeer moss is also known as "reindeer lichen" or "caribou moss" and is a popular food for other animals as well. It's a good source of energy and fiber for reindeer and is also used as a natural herbal remedy for humans.