Netherrack

Netherrack was a material used in "Netherrack Thermocouplings", a component of the TARDIS. (NOTVALID: Doctor Who Minecraft)

Behind the scenes
was a in Minecraft typically found in, a hell-inspired dimension accessible through an obsidian portal lit with a flint and steel. If lit on fire, it would never stop burning unless put out by something else in the game.

The block was used in various builds in NOTVALID: Doctor Who Minecraft, such as a recreation of the Capitol on Gallifrey, a planet seen in a transmission from Ben, and the ground on which Stampy walked in a behind the scenes section.