Dalek fender

Human historians in the post-Time War universe observed that, during the Dalek Wars, most citizens of Earth secretly believed that the future of the human race was to be ground beneath a Dalek fender. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)

The Dalek Earthforce had larger, additional fenders at the bottom of their base unit. (TV: The Dalek Invasion of Earth)

The gold and black Dalek Supreme was distinguished from its subordinates by its taller fender. (TV: Planet of the Daleks)

The New Dalek Paradigm was distinguished from their predecessors by their taller fenders. (TV: Victory of the Daleks)

In the rebuilt Dalek City, one older Silver Dalek model sported a bronze-type fender. (TV: The Witch's Familiar)

Behind the scenes
The Daleks seen in the theatrical films Dr. Who and the Daleks and Daleks' Invasion Earth 2150 A.D. had taller fenders than their televised counterparts. These fenders were removed for movie props which were used in The Chase, creating a new Dalek variant.