Red weed
From Tardis Wiki, the free Doctor Who reference
Red weed was a type of plant from another dimension that could stop time.
When an dimensional opening was created on the seventh planet of the Althosian system, red weed began to spread from the opening across the planet. Anything that contacted or went over a patch of it was frozen in time. If it was a living creature, it would become crystallised and die. Jarak Romer and Butler were killed by the weed.
After the gap was closed, the weed lost its ability to affect time, turned a chalky colour and crumbled into dust. (PROSE: The Pit)
