The Orb Of Hydra was an item owned by Selwyn and Tallulah in the cartoon show episode "The Gargoyle Of Quarrel Castle". Selwyn had won it as a prize at a wizard's ball. Unfortunately, the orb contains a three-headed hydra that grows to giant size when it is opened, which is why Selwyn tries to keep it in a safe place and keep it from being kicked.
However, the orb was knocked out of its resting place by Selwyn and Tallulah's pet Tharp when he was searching for his ball to replace the one he had lost when he tried to play smurfball with the Smurfs, and was mistaken for Tharp's ball when he took it to play smurfball. Tharp had kicked the orb and released the hydra within that tormented the Smurfs, with Tharp trying to bravely distract it, until Selwyn and Tallulah showed up and shrank the hydra back down to size where it re-entered the orb that it came from.