It's easy to farm hundreds of Vertebrae in pre-hardmode world with simple lava trap system. Lava Bucket and any solid blocks are essential, wire system with actuators for more comfortable farming are optional. Make sure you have Water Candle in your hand and a few Battle Potions to maximize enemy spawn rate. Note that this tactic can be applied anywhere, although biomes with enemies able to penetrate through walls (e.g.: Dungeon, Underworld, etc.) might be risky.
- Added to the game.