Stone Dalek

The Stone Dalek was one of the progenitor Daleks, left an 'after image' when Dalek history was temporarily erased in a world where the universe was destroyed in 102 A.D, destroying all worlds and stars throughout history, except for the Earth and its moon.

History
The stone Daleks were the Progenitor Daleks present at The Alliance's sealing of the Doctor in the Pandorica in 102 A.D. As the cracks in time continued to run rampant across the Universe, Dalek history was erased, leaving the stone Daleks as 'after images'. The Pandorica contained atoms from the original universe, from before the cracks started to erase events, and had the ability to sustain life.

Light from within the Pandorica reactivated one of the Daleks, albeit with limited power. The Dalek shot the Doctor, managing to severely wound the Time Lord, but at the cost of depleting its energy reserves. It was then confronted by River Song. Initially disbelieving that River would destroy it, based on the fact that she was one of the Doctor's companions, after checking it's records and discovering who she was. The Stone Dalek, realising River could shoot it through the eyestalk with an alpha meson gun, killing it, begged for mercy and was unsuccessful.

When the Doctor reset the universe and timeline, the Stone Daleks, along with all things that were destroyed throughout history, were restored to their original form and place in space and time. (DW: The Big Bang)

Behind the Scenes

 * This Dalek was the first to actually be heard crying "Mercy". The lone Dalek in DW: Dalek cried for the Doctor to "Have pity" (as did Davros in DW: Remembrance of the Daleks).
 * It is unknown which Dalek of those present under Stonehenge this actually is. The lack of a deep voice does suggest that it is not the Supreme. Its longevity may mean that it was the Eternal.