Thidaxx

Thidaxx also known as Tar monsters, were a species of cave-dwelling predatory creatures native to Taul. They had squirming tentacles and shark-like heads covered in eyes. At some point prior to the Battle of Takodana, a group of droids stranded on Taul were attacked by tar monsters. After ripping 2MED2 apart and destroying CO-34, the monsters snatched C-3PO's left arm, attempting to drag him away too. However, O-MR1 held onto his fellow droid, and thus the monsters were only able to rip C-3PO's left arm off.

Text and facts from the “Thidaxx” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.