I might port this mod to 1.16.x in future, but I also might not. We'll see as time goes on.

It's a work-in-progress mod that adds resources and crafting items, mechanics, mobs and shared code systems that will be used by Convenient Additions 2 and Convenient Technology.

The resources added are:

Molten Cores: dropped by Blazes and rarely by Magma Cubes
Ender Hearts: dropped by Endermen and rarely by Endermites
Dragon Scales: dropped by the Ender Dragon
Arcane Dust: rarely drops when mining Redstone or Lapis Lazuli Ore, also rarely dropped by Witches
Diamond and Emerald Shards: rarely drops when mining the corresponding ore, 4 can be crafted into the corresponding gem
Geodes: rarely drops when mining Vanilla Overworld Ores that work with the the Fortune Enchantment
right-clicking them opens them yielding random ore themed items(dusts, gems, coal, nuggets, shards, etc.)

The crafting items added are:

Iron and Gold Rods: like sticks for iron and gold (works with OreDictionay)

The mobs added are:

Undead Miners: modified Zombies that spawn in Abandoned Mineshafts, carry a random Enchanted Pickaxe and can drop mining themed items such as ores, torches and their own pickaxe of course

The mechanics added are:

Slime Harvesting: right-clicking a Slime with a Bucket harvests its slime but also damages it, also works with Magma Cubes

It also adds a Wrench.

only relevant for mod devs: The code systems added are :

Energy System: a new Energy System that supports different types of energy, default Energy Types are Redstone and Ender Energy, different types of energy have differing Efficiency (work done per unit used) and Entropy (heat created per unit used)
Heat System: still work in progress but machines will heat up when using energy making them less effective and eventually explode
Entity Stack System: allows storing and transferring Entities
Soulbound: a handler for Soulbound Items
Ender-Proof: a handler for Ender-Proof Blocks (Endermen can't teleport through them)
GUI Widget System: a new Widget System for GUIs
Config Loader System: a simple system loading configuration and config guis from annotations

Convenient Foundation