Plaster of Paris
From Tardis Wiki, the free Doctor Who reference
Plaster of Paris (also known as Gypsum) was a type of plaster, a building material used for the protective or decorative coating of walls. The Fourth Doctor once used plaster of Paris to make an impression of a Skarasen's teeth by pouring the material into several large holes found in the wreckage of the Prince Charlie oil rig. (TV: Terror of the Zygons)
