The podcast episodes provided focus on the topic of speculative biology, which involves proposing plausible scientific explanations for the unique traits and abilities of fictional creatures.

In the episode 'The Monstrefact: Alien, Part 1 - The Engineers', the host examines the enigmatic Engineers from the 'Alien' universe, speculating about their nature, origins, and capabilities in creating lifeforms.

The episode 'The Monstrefact Omnibus: Star Trek' takes a similar approach, exploring the speculative biology behind various Star Trek species, such as the Andorians, Tribbles, Ceti Eels, and Horta.

Finally, the episode 'The Monstrefact: The Flight of Dragons' delves into the proposed scientific mechanisms behind the flight of dragons, as described in the book 'The Flight of Dragons'.