Boulder
Boulder Class dragons are tough and associated with the earth. They can eat rocks, which many of them melt within their stomachs and regurgitate as lava blasts. Although they have small wings compared to their body size, they are able to fly as fast and as high as most other dragons can. According to Fishlegs in Rise of Berk, Boulder Class dragons aren't picky eaters.
GRONKLE
WHISPERING
DEATH
DEATH
SCREAMING DEATH
HOTBURPLE
ERUPTODON
CATASTROPHIC
QUAKEN
QUAKEN
SENTINEL
CRIMSON
GOREGUTTER
GOREGUTTER