Ore Crawlers

So I have this idea for there to be these insect like creatures made of stone and gems. They are known as the ore crawler. These hostile mobs will live in the lower parts of the caves. They can be made of different ores, and if they spawn in the Amethyst Geodes, they can spawn as an amethyst crawler. They will drop 1-3 of whatever material the are made of and some cobble stone. And depending on what material they are made out of, they will have more health and more attack damage.