Stone Monolith

Stone Monolith is a crafting item. To craft a Stone Monolith, you have to get 5 Tough Material (Drop from tough bloons, like lead, ceramic, T.O.M., etc.) Stone Monoliths block bloons in it's path from continuing forward. It has 500 "Hp" and bloons deal their RBE's worth of damage to the Stone Monolith every second they are stuck on it. It basically looks like a giant stone wall.