Mountain Fort came to alive to smash the city.
Secret Mountain Fort Awesome is really supposed to be a mountain with an eyes and mouth formation made into it. But instead Secret Mountain Fort Awesome is actually a living breathing organism. It's first apperance being alive was in the episode Secret Mountain Fort Love. where Secret Mountain Fort Awesome began sprouting arms and legs much like Gweelocks and ran around the over grounds smashing stuff and fell in love with another mountain. It may possibly be another Disgustoid. In the Episode Road Trippin they used him as a car and drove him around town to smash stuff.