The word "沙虫" is formed by combining the character "沙" (shā), meaning "sand", with the character "虫" (chóng), meaning "insect" or "worm". This creates a compound noun where "沙" specifies the habitat or environment, and "虫" denotes the type of organism, resulting in a literal meaning of "sand worm", which refers to a worm-like creature typically found in sandy areas.