Thorn Weeds can only be found in Ancient Waterworks as a fairly common enemy in the area. Thorn Weeds often walk around an area until the spot Wario and attack by firing their spikes at him. Because they are made of metal and covered with spikes, Wario cannot damage them by jumping on them, Shoulder Bashing them, or even using Cosmic Wario's lasers. Dragon Wario's fire breath is the most ideal way of taking out Thorn Weeds. Genius Wario's Ultra Hand can be used to defeat Thorn Weeds as well.