Diamondillium

Diamondillium is an ultra hard mineral created by Dr. Ogden Wernstrom. It was used to encase the Earth to protect it against the Electromatter tentacles, but failed.

There was a contest of Death-Ball between Farnsworth and Wernstrom to decide wether Dimondium or Diamondillium (respectively) would be used to protect Earth from the tentacles, Ogden Wernstrom was the victor, so Diamondillium was used.