Seed Pod

The Martian Seed Pods were not named in the serial.

The Martian seed pods are a type of fungus, either native to Mars or created by the Ice Warriors. These seed pods function by breaking down plants and biological matter (like other fungi). In an oxygen rich environment though, these seed pods grow at a much faster rate. This fungus was also released in a cold part of Earth, though this might have just been for the Ice Warriors' convenience.

These seed pods go through several stages. The first stage is a white round pod (hence the name). If exposed to air, it will swell up and release a cloud of spores. If these spores land on biological matter, they will start growing and sucking up oxygen. These spores grow into a thick foamy substance which quickly covers the area. This foam will then grow pods, which repeats the process. It was estimated that after the pods covered sufficient area on Earth, it could bring down the oxygen content to 20% of normal. This would kill the humans, but would be perfect for the Ice Warriors.

These seed pods are immune to brute force and most acids. On the other hand, on contact with water these seed pods shrivel up and die (due to the lack of water on Mars). (DW: The Seeds of Death)