The Sandworm mob - creating sand

New mob, the sandworm that creates sand (yes a bit of Dune vibes).

It lives in the underground / caves of the Desert biome. It can enter and exit (cave specific) blocks like Silferfish and is a neutral mob. 

It drops sand likewise a sheep gets its wool but it dispeces the item on an area when it exits a block. The mob needs to be kept in the dark and needs a specific block to create said sand if the player want to make a farm out of it. (Example: Sandstone)

Neutral mob, meaning if you hit it, it wont produce sand for a while, though it wont attack the player.

You can enclose the mob though with blocks he cant get through, and this way it makes a little of a challenge to create a farm out of it. The rates of getting sand is debatable but it creates sand which already is a great way to have a way getting sand without destroying the entire desert biome as that is the only way to get lots of sand to be used.