An amorphous, self-replicating substance found on Gallifrey in the Pool of Rassilon. Chronoplasm is the combined byproduct of discarded, underground matter, used in temporal experiments by the Time Lords and hyper-dimensional energy from a time/space fissure created by those experiments. The substance attaches itself to any organic matter, instantly spreads over its entire surface, then erases it and all memory of it from time, as if it never existed. Chronoplasm is used in the apparatus called Time-blot, which is possessed by the space vigilante called the Janitor.