[Ore] Seashells

[careeoki]

Proposal for seashells as a tool material and fun building block.

Physical properties

• hardness in Mohs scale: ~3
• low density

In-game properties

• behavior similar to gemstones
• It's also a cool decorative block for beaches.

Modifiers

• ??? Swing time is lowered while wet (while underwater, when it's raining, etc. "wet" could be a status effect)

Spawn rules

• Generates as an ore in beach biome sand.

related to #1269