Handmines were mutants used on the planet Skaro during the Thousand Year War. They appeared in groups, and would take hold of and pull individuals underground. They resembled decomposing hands with an eye in the centre of the palm.
They traveled by tunneling under the earth and possessed incredible strength; a single handmine was able to pull a full grown kaled beneath the earth with considerable force.
They were drawn to sound and movement. If a person was still but making noise, they would rise up from the ground to search for the target. Once they had found someone, they would turn to face them.
As a child, Davros found himself surrounded by handmines. A soldier named Kanzo tried to help him, reminding him to stand still before being pulled underground. (TV: The Magician's Apprentice)