Petrified Wood

Petrified Wood is a collectible found in Knock on Wood. There are 6 in the game, and they are found after defeating bosses. All of them are required to unlock the final world: Forest in Flames.

Backstory
The One of Wisdom enchanted six special pieces of petrified wood, and made them the only way to open the doors of the Treant Temple. When all six are placed in their slots, the doors will open. In times of emergency, they would be taken out the keep the people inside safe. During the events of Knock on Wood, General Ryvok runs into the temple with Allister, and removes the six pieces, barricading himself inside, and the six pieces are given to his henchmen and the reincarnated Treant elites, hoping Woodrow would not be able to defeat them.

Usage
You must acquire all six of them to unlock the final world of the game.