Crawlers

Crawlers are gigantic, carnivorous worm-like creatures with armored hides that live deep under the earth. They are unable to borrow through solid rock or similarly hard material, so they are only found in areas with soil, dirt or sand. 
References:
-https://www.tumblr.com/search/dnd%20monster
-http://www.imdb.com/title/tt0100814/
-http://news.nationalgeographic.com/news/2011/06/110601-deepest-worm-earth-devil-science-animals-life/