Chalk caves

A chalk cave would be a cave with unique chalk blocks which look like a stone block with a stronger white clay. In chalk caves spawn zombies which have a layer of chalk on their skin which slows them down and gives them a stronger resistence than normal zombies have. They drop chalk shards, rotten flesh and iron nuggets. With chalk shards you can craft an armor which is slitly better than an iron armor and a chalk schield which has a better durability than an iron schield.