Use in Super Zero
It is a volcano that is next to the Dimmsdale Dam which Super Not-Cosmo/Cosmo prevented from exploding by putting a cork in its mouth. It later explodes together with the dam and the people blamed Cosmo for this.
Use in Nega Timmy
In "Nega-Timmy", it was inactive but Nega Timmy's plan was to reactivate this volcano (by having a satellite crashing down on the top of the volcano) and destroy the Dimmsdale Dam causing a huge lava wave to destroy the make-up factory. This was the reason that this volcano is active in Super Zero.