The Telfi are a weird sapient species which feeds on pure radiation and likewise travel on highly radioactive ships. The Telfi are colonial creatures, coming together in large numbers to form living gestalts which act as a single individual and are a true example of a collective intelligence.
Individually, Telfi are very small, beetle-like and only barely sapient. For a Telfi, there's no worse feeling than being alone, separated from the gestalt. They communicate with each other through powerful telepathy and require extremely hot, radiation-rich environments to live. Nonetheless, an excessive amount of radiation is unhealthy and in some cases even lethal to them, just like too much food can cause food poisoning or indigestion on Humans. The Telfi physiological classification is VTXM. To talk with other species, they use a "staccato clicking and buzzing language".
Some individual Telfi units are specialized for a certain function much like a cell in a Human body, although the Telfi appear to be able to survive individually for considerable periods of time. Telfi may operate on gestalts of a hundred and even five hundreds units. A Telfi who has lost its ability to join minds remains alive, but becomes the equivalent of a "hopeless cripple" in their society
Appearances - Sector General by James White