The Geonosian hydras were huge carnivorous insectoid creatures with three heads, though some hydras could have more than three—which would not be considered a mutation. Hydras were amphibious and lived beneath the few seas on Geonosis, like the Ebon Sea. As a result, it is presumed the species was rare on Geonosis. Geonosian hydras preyed upon less defended Geonosian hives. They were sometimes used as the main event in Geonosian gladiatorial fights, where they would be pitted against a large number of armed gladiators.