- You may be looking for the planet.
As Davros threatened to the Tenth Doctor, the reality bomb would have turned people, planets and stars into dust, which would become atoms which would ultimately become "nothing". (TV: Journey's End)
According to Amy Pond, petrichor was the smell of dust after rain. (TV: The Doctor's Wife)
As observed by the Ninth Doctor, moon dust was among the exhibits on display within Henry van Statten's vault in 2012. (TV: Dalek)
Rose Tyler gloated to Dalek Sec that she took the time vortex into the head of the Dalek Emperor and turned him into dust. (TV: Doomsday) Indeed, while she was possessed by the Bad Wolf entity, Rose was responsible for the utter destruction of the Emperor's half-a-million strong Dalek fleet. (TV: The Parting of the Ways)
The dust in sunbeams was Vashta Nerada. (TV: Silence in the Library [+]Steven Moffat, Doctor Who series 4 (BBC One, 2008).)
Sutekh's Dust of Death was a deadly dust that he spread throughout the universe, causing any living being it came in contact with to instantly crumble to dust. Its effects were reversed when the Fifteenth Doctor banished Sutekh. (TV: Empire of Death [+]Russell T Davies, Doctor Who series 14 (BBC One and Disney+, 2024).)