Hydroid Medusas, formidable jellyfish cyborgs augmented with armor and various cybernetic improvements, originated from the Karkarodons of their homeworld, Karkaris. These Hydroid Medusas saw action under the command of Riff Tamson, a Commander within the Confederacy of Independent Systems employed by the Karkarodons, during the Battle of Mon Cala. Their near-invulnerability rendered them impervious to blasters and lightsabers, which proved ineffective against their defenses. The Republic and Mon Calamari armies suffered significant losses and were compelled to withdraw. The arrival of Republic reinforcements, specifically the Gungan Grand Army, changed the tide, as their boomas demonstrated the capacity to inflict some harm upon the Hydroid Medusas.