There is a new physics blog at xkcd called What If? Each week it discusses a question of pressing scientific interest for a general audience. If one loses the train of thought one can always consult the diverting illustrations, which feature those lovable xkcd stick figures.
The issue this week is particularly pressing — if you’ll forgive the pun — as they take up the question of what would happen if one assembled a planet-sized sphere of moles (or comparable small rodents). It’s pretty awful:
The outer surface of the planet radiates heat into space and freezes. Because the moles form a literal fur coat, when frozen it insulates the interior of the planet and slows the loss of heat to space. However, the flow of heat in the liquid interior is dominated by convection. Plumes of hot meat and bubbles of trapped gases like methane—along with the air from the lungs of the deceased moles—periodically rise through the mole crust and erupt volcanically from the surface, a geyser of death blasting mole bodies free of the planet.