Archeology
Buy a brush, hold right-click on suspicious sand or gravel, and you might get a fragment. Spend fragments to discover random furniture pieces, then buy the ones you've discovered.

How It Works
Brushes come from the Brush Shop in /archeology. Higher tiers clean a block faster. Brushing works like vanilla, with the same animation, sound, and pottery shards, but each finished brush also has a chance (roughly 10-35%) to give you a bonus fragment.
Fragments are real, stackable items, so you can drop them, trade them, or keep them. In the Codex, the "Discover Furniture" button takes 3 fragments and unlocks one random furniture piece you haven't found yet. The order is random, so you and a friend probably won't unlock things in the same order.
Once a piece is discovered, you can buy it with money from the same Codex screen. Discoveries and purchases are saved permanently and survive restarts.
The Archeology area
The Archeology area resets every 6 hours. It's brushing only: no breaking blocks and no PvP.
Commands
/archeology(aliases:/arch,/dig) - open the archeology menu: Information, Brush Shop, and the Codex