Desert worms and Deathworms

The Mongolian Death worm is a mighty beast of legend, that has incited fear in many who heard of it. These could spawn in a desert or rare desert biome. These worms could spit acid, drag players under the sand, and bite. It would also be cool to see a passive form of worm which can be farmed for useful products, like fertile soil, and other bi-products. The worm is preferably kept alive, and happy. The passive worm could have a smooth texture, while the Death worm has spikes. This would add a danger to the desert, and possibly fill a void left by the Great Hunger.