Amethyst Rats

Minecraft at this time has not a lot of smaller hostile creatures that can actually pose a threat to the player. The crystal rats would be almost chicken-sized and would be slumbering, hibernating inside of amethyst geodes. But this creature both relies on sound and sight, the creature will only awaken itself if a player creates a unpleasant sound alerting in the pack the creature has little vision barely seeing around them making it easy to get rid of them but if you can't run they will kill you quickly. 

They always spawn in small herds ranging from a least 3 to 7 crowded together to stay warm, The creature if it bites you can give you the crystallizing effect causing the player to slow down slightly and cause the players screen to get a similar effect to the freezing effect. These creatures would also be useful, if probably contained they can randomly increase the production time of amethyst.

These rats also could drop lwine, Lwine would be a material that could be used to craft a quiver, the quiver could in the place of the chest plate or the offhand and could hold 128 arrows inside of it. But it comes at a cost a is very fragile it would have the durability of gold and could be fixed with a anvil but only takes damage it self when you as the player are hurt while using it.