Beautiful Boulders
regulus

Procedurally Generated Rocks with (pretty) Accurate Collision Boxes

More Coral
Nathan.S

Adds coral in more colors.

Randomized Map-specific Ores
Piezo_

Adds two randomly created ores to each world with varying properties depending on the world's seed

Unstable Caves
M BLOC

Some stones may cave in if punched, making underground expeditions more risky.

golden lava
Giga_M

add golden lava

Trucraft
mt-mods

An alternative crafting system done entirely in the world.

Purple ore
X-DE

Adds new purple ore to floating islands and caves from height 200 to 31000.

Obdy
Sires

Adds some pretty OP tools :)

treasures
ademant

Treasure nodes with useful items

Underground Survival Lighting
Arkatron

If you like underground light in survival, use this mod, it can help that.

Dirt Tunneler
Neuromancer

Makes dirt deeper and you can tunnel through it just by walking through it. Press spacebar/shift to tunnel upward/downward with auto placed ladders.

Fly-B-Gone!
Hugues Ross

Hides butterflies/fireflies

Sun Flowers
Hybrid Dog

This mod generates flowers which close their heads at night.

Sticks Stones
MikeRedwood

Makes Sticks from leaves and scatters small stones

Archaeology
SkyBuilder1717

Adds an looting and API in archaeologing

Floof
Momo

Add BicBiomeCraft inspired biomes, tools, and items.

Silver
Jackknife

adds silver ore and tools

Mud
Blocky Player

Adds stylish mud blocks and even blocks you can walk through. Setup traps, secret rooms and much more!

Too many ores
TeufloV

This adds 53 new ores. But most of them are useless.