Caves and Cliffs: The Dweller, Rockshell Armor, and Renewable Stones

Dwellers are a neutral mob that spawn only on deepslate, except they don't spawn in lush caves. If the space they're occupying has too much light, they become hostile (Light level 8 or above, only happens if a player places a torch near them, because they move away from light sources naturally.) Once hostile, they stop caring about light sources and will charge at the player.

Their shell negates all power and sharpness enchantments, however they are weak to bane of arthropods and piercing. 30 HP in total.

Dwellers drop dweller chitin, which can be crafted into a storage block, that when broken breaks all other nearby chitin blocks. 8 chitin crafted around copper makes a rockshell ingot, which upgrades leather armor in the smithing table. Rockshell armor increases the range of building and breaking blocks, and it increases your mining speed, (not to the point of instamining, that should be kept for the beacon.) With every piece of armor, range increases by 1 block. With haste 2, it allows you to instamine deepslate. It only has 5 armor points in a full set, and doesn't affect melee range.

Rockshell ingots can be crafted with amethyst shards to make a magnet that increases item pick up range, and any block you mine is instantly put in your inventory.

Dwellers shells can be changed into a different stone type if you feed it that stone, they can also be bred with glow lichen. This allows renewable stone types of all dimensions as well as earthy materials like gravel, clay, and sand.