Taprisiot

"Taprisiots" are a fictional species in Frank Herbert's science fiction novels, "The Dosadi Experiment" and "Whipping Star".

Taprisiots (generally called 'Tappys' by humans) appear to be stubby chunks of wood, almost like logs with their branches broken off. Their value to other sentients is that they can communicate directly with each other telepathically, and can create telepathic communications channels between other sentients with their mediation. They sell their services as communications channels, and have become indispensable to the workings of the pan-sentiency.

Among other users, agents of the Bureau of Sabotage are sent out on especially dangerous missions with 'Taprisiot monitors': a Taprisiot maintains a telepathic link to the agent, and at the moment of the agent's death, the entire circumstance and contents of the agent's conscious mind can be made available for study.

It's speculated that Taprisiots are, in some sense, immature cousins of Calebans, who have far greater access to the realm that the Taprisiots use for telepathy. Caleban interaction with sentients is through contracts to provide jump-doors and other, more specific, services.

The theme of a species providing a uniquely valuable service to other species is an echo of the economic arrangement between planets in Gordon R. Dickson's Childe Cycle series of novels. In those novels, humanity has psychologically splintered into distinct cultures that are co-extensive with their planets: the inhabitants of the planet Dorsai, for example, are the foremost warriors in the universe, and sell their services as mercenaries; Cetans and Newtonians are science worlds, contracting their citizens out to other worlds as scientists, technologists, and engineers. Lacking a suitable currency across the different worlds, the market for skilled contract workers is the essential unit of barter between planets and cultures.