Trobulum

Trobulum is a silvery-white element. It is not only the toughest substance known, it is one of the rarest: Trobulum is found only in the Gpii System.

Web of Deception
When Lockdown was hired by Blackarachnia to secure a giant spider from Archa Seven, he installed a cage made of Trobulum in his spaceship to transport the spider in. The empty cage was later found by a small group of Autobots and humans when they infiltrated Lockdown's ship on Earth.