A Link to the Past
These enemies exclusively appear in the Desert of Mystery, located just outside the Desert Palace. They are sand creatures that will pop up from underground and rapidly move towards Link. With their long arms, they cover a lot of ground and are worthy enemies.
Geldman are often accompanied by enemy Vulture, as well as the environmental threat of Land Mines and Cacti. Alone they are not much of a threat, but when there are multiple enemies on screen at once, they can be difficult to avoid.
After burrowing back underground, the Geldman will reset itself and will come back up from its initial location. Any damage that is done to the Geldman will be retained even after it burrows underground. It will take four slashes with the Fighter's Sword to defeat. Alternatively, Link can hit it four times with the Boomerang to do it in. Later on as Link acquires more powerful weapons, a wide variety of them can be used to defeat Geldman.
A Link Between Worlds
Geldman appear exclusively in the Desert region of southwestern Hyrule, located just outside the Desert Palace. These enemies will pop up from under the sand and quickly move towards Link. In A Link Between Worlds, the Sand Rod can be used to bring a Geldman out of the sand, revealing the lower half of its body. Embarrassed or slightly out of place, the enemy will then erratically run around the desert. At this point, Link can then defeat it with the Master Sword.