The Quarks are small robots with a box-shaped body. They walk on two legs with boxlike feet, and their head is spherical with four crystals jutting out at either side and one more crystal at the top. Two arms fold out from the body, and on the end of each arm is a metal clamp called a force unit. These force units can be attached to machines to power them, attached to devices that are used to cause pain, or they can be used as ultrasound weapons that paralyze or cause immense destruction. The force units must be reloaded after firing.
The Quarks obey the orders of the Dominators. Ordinarily they remain on the Dominators' home planet, but the Dominators intend to control the entire galaxy and their war mission is spreading to colonize others. In order to do this, the Quarks must be taken from the home planet to aid them, and hence the workforce on the planet must be replenished with slaves.
There are apparently no sensors built into the Quarks, or if there are, they are not often used, as they cannot sense the presence of nearby humans (or Gallifreyans or Dulcians). Due to their bulky size, the Quarks cannot climb, but they compensate for this by being able to fire upward. Quarks also have the ability to bind people to surfaces using molecular force. They can also link with other machines and record all their technical data, during which they spin in circles.
Quarks have no free will of their own - they are little more than machines. They can speak, however, in high-pitched voices, and can judge the best course of action, though if a Dominator is present, the Quark will ask for confirmation. The status of all Quarks is monitored by lights in the Dominator ship, though they are not easily destroyed - energy weapons or large boulders do put them out of action, though. Despite this, the Quarks do not have an unlimited supply of energy, and their power cells can run out. They seem to operate off a separate reserve of energy that is replenished with the power cells, as the Quarks must recharge from time to time. When they recharge, their arms fold in and out. Falling power levels also decrease the accuracy of their aim.
