- "Your aqua droids are no match for the Mon Calamari. What makes you think these secret weapons you brought from your homeworld will fare any better?"
"They are half machine, half monster. We call them Hydroid Medusa. They are invincible."
- ―Nossor Ri and Riff Tamson on Hydroid Medusas
Hydroid Medusas were cybernetically enhanced jellyfish developed by the Karkadons as a bioweapon in underwater warfare during the Clone Wars.
The Hydroid Medusa were large behemoths that were modified and designed for underwater combat. They had onboard power plants, which made their tentacles powerful enough to kill any biological being with one sting. Unfortunately, they could be short-circuited if near any other electrical source. They were also invulnerable to blaster bolts and even lightsabers. They could also be destroyed by vehicles on suicide runs.
Commander Riff Tamson brought in a number of these during his conquest of Dac. They were brought in on CIS landing crafts. Durring Tamson's 2nd attack, the Hydroid Medusas were able to force Prince Lee-Char's and the republic forces to retreat. When the gungans attacked, they were able to stop couple of the Hydroid Medusas but the Gungans were quickly captured. Unfortunately, Tamson lost the battle along with his life.