Gerunes are enemies in Spirit Tracks.
Gerune are initially invulnerable to Link's sword slashes. Instead, Link will need to use the Sand Wand on the enemy, causing it to stiffen up and stop in its place. Once it stiffens up, Link can pick up Gerune and toss it to the side to damage it, or he can simply slash away with his sword.
One Link tries to use the Sand Wand, Gerune will try to dash away, so it is best to use the Sand Wand where it forces Gerune to move towards a corner.