Love and War (Doctor Who) - Hoothi

The fungoid monsters in this novel, the Hoothi, were named in a throwaway reference in the 1976 Fourth Doctor serial The Brain of Morbius. A form of sentient fungus-like biomass, the Hoothi sought to expand their influence throughout time and space. In order to achieve this, they wished to overthrow the Doctor's homeworld of Gallifrey. They believed that by conquering Gallifrey they would gain the ability to spread their spores to all parts of space and time.

As in the throwaway line in The Brain of Morbius, the Hoothi travel in gas filled dirigibles the size of a small moon. The gas comes from the decomposing corpses consumed inside. The dirigibles are invisible to almost all forms of tracking.

Using Hoothi filaments (resembling white fibres) they were able to forcibly control the minds and bodies of living (and deceased) lifeforms and absorb the knowledge and memories of infected intelligent beings to expand their own knowledge. In this respect, they resemble a biological equivalent to the Cybermen. The filaments are blown throughout time and space and can infect people without their knowledge and lie dormant for years until activated.