Thorn bush is a plant grown from a thorn bush seed. When touched or harvested, it inflicts damage on the player, similarly to a spike. However, it doesn't deal damage to the player that planted it and his/her teammate. Having harvested thorn bushes in the inventory do not inflict damage to the player.
16 thorn bushes can be used to craft 1 thorn bush seed.
The thorn bush was added in the "Merry Christmas" update.