Well, reindeer poop is called "reindeer pellets" because it looks like small brown pellets. It's made of a mixture of the deer's diet, which consists mainly of moss, lichen, and grass. The pellets are formed in the deer's digestive system and come out as small, round balls. They can be hard or soft depending on the deer's diet and health. The pellets can also contain small amounts of undigested plant material or seeds.