Geozard

Geozards are marine-dwelling salamander warriors likely based on the Kappa of Japanese folklore (hence the suffix "zard" rooted in their reptillian inspiration, and "geo" prefix signifying their land-based preference) which appear in Phantom Hourglass and Spirit Tracks.

Geozard
These sword-swinging enemies boast powerful armor and shields that are capable of deflecting any initial attacks. They are mainly found guarding something of notable importance and in order for Link to continue his quest, they have to be defeated. If Link steps into their territory, they will jump out of the water, and make a threatening roar at him. Otherwise, they can also be found attacking ships. Link can use his boomerang to trace a path to the Geozard's vulnerable backside. If the boomerang is successful in hitting its backside, the Geozard will be stunned for a short period of time. This gives the young hero a chance to defeat the monster with a number of sword strikes.

Geozard Chief
Geozard Chief is a stronger, fiercer Geozard that appears rarely in Spirit Tracks. It is more powerful than the normal Geozards, as it is able to breathe a stream of flames at Link and it is able to jump huge distances at will. However, it shares the same weaknesses as weaker, normal Geozards. To defend against the flame spewing attack, Link can hide behind Phantom Zelda. Interestingly, whenever Zelda possesses a Wrecker Phantom, she can simply roll into these foes, and in three of her hits, they are defeated, without Link even having to touch them; this technique comes in handy in the final room in the last run-through of the Tower of Spirits, where three Geozard Chiefs threaten Link at the same time.

Weaknesses
The proper way of dealing with Geozards is by hitting them in the back with the boomerang, which stuns them and gives Link enough time to attack with his sword. However, in Phantom Hourglass, after the young hero has obtained the Hammer, he can strike them twice with it for a quick kill. In Spirit Tracks, Zelda can distract it while possessing a Phantom, allowing Link to attack its back. After acquiring the Whip, Link can defeat Geozards by himself. He needs to use the Whip to snatch their shields and then attack them with his sword.

Trivia

 * In Spirit Tracks, the Geozard Chiefs wear what seem to be Knight's Crests.
 * Geozard's Japanese name appears to be a portmanteau of the Japanese word for fish,, and Amazon, which, in turn, is derived from "ha-mazan", an Iranian ethonym for a group of warriors. Thus, Gyomazon literally means "Fish Warrior".