Ultragem

This mysterious Gem was hidden in Castle Grimm on the Planet Gremlyn and has the strange power of transforming the molecules of anything it touches to it’s holder’s wim. Xenor Krell tried to steal the Ultragem but she only managed it thanks to Amy Rose and Tekno who she duped into believing that she needed it for the common good. Xenor Krell used the Ultragem to defeat Serpentius, then transformed the castle into solid silver. When she turned on Amy Rose the silver castle reflected the Ultragem’s rays and both Xenor and the gem were reduced to vapour. It appeared in Sonic the Hedgehog Comic #152 and 153.