Heart of Stone
Roots: There are references to Jammie Dodgers, the Cookie Monster, the Apollo 11 moon landings, and Scooby Doo.
Continuity: The alien bacteria are space-faring and landed on the Moon in a spherical black meteorite three point nine billion years ago. They remained dormant until the Apollo mission unwittingly brought the rock back to Earth inside sample 247, the “Heart of Stone”. The bacteria were awakened when the rock was bombarded with UV radiation and, having mutated, built a body, Athrocite, based on the first animal organism it has encountered for nearly four-billion years, i.e. humans. The bacteria can use molecular reconfiguration to turn anything into Moon Rock. Hence, everything Athrocite touches turns into moon rock. The process is highly unstable, and therefore reversible, until a critical amount of matter has been transformed. At that point the effect would be permanent and unstoppable and would spread across the whole of Earth.
The Doctor, Amy, and Rory eat lamb stew at the farm. The Doctor drives Chris’ sports car. The Doctor temporarily allows himself to be turned into animate Moon Rock so that he can communicate with Athrocite. Whilst made of stone, he chips a bit off his finger, causing him to require a plaster when the transformation is reversed.
There are many silicon-based species in the Pron-Kalunka Galaxy; some of their civilisations use granite as the base matter for all their technology.
Links: The Doctor recalls meeting H. G. Wells (Timelash) and visiting the Marie Celeste (The Chase). Rory recalls visiting fifteenth century Venice (Vampires of Venice). Amy notes that she has been to the Moon (Apollo 23).
Location: Conway Farm, England, and the Moon .
Future History: The Doctor claims that events similar to those in Independence Day happen in 2109.
Unrecorded Adventures: The Doctor used to spar with Mohammad Ali.
The Bottom Line: A story clearly designed purely to appeal to kids, Heart of Stone ditches Baxendale’s usual dark horror and instead opts for ludicrously implausible pseudo-science. It is, nonetheless, light-hearted fun.