what is the toy called glow worm?
None ... The Glow-worm is a tiny, wormy dragon that lives in caves and other darkened areas. They are utilized at night as a light source by Vikings. Glow-worms are classified as Cave Dragons in the Complete Book of Dragons, but as mentioned as being Nanodragons in How to Train Your Viking. This dragon's name has been spelled in two ways in the Books: Glow-worm and Glowworm.