Prototaxites stellaviatori

P. stellaviatori cultivated on the Discovery

Prototaxites stellaviatori was a species of fungus, casually described as a mushroom.

Delta2 terraforming mycelium strain

Lieutenant Paul Stamets holding a container with his original Prototaxites stellaviatori sample.

The species was composed of exotic material found not only in normal space but also in a discrete subspace domain known as the mycelial network. Its fungal roots, or mycelium, fanned out into infinity across the universe to form the mycelial network. (DIS: "Choose Your Pain")

In 2256, a strain of P. stellaviatori was grown in the cultivation bay aboard the USS Discovery. Its mycelium spores were harvested for use in the Discovery's experimental spore drive. (DIS: "Context Is for Kings", "The War Without, The War Within")

In 2257, the Class 4 moon Delta 2 was terraformed using the species in order to replenish the Discovery's supply of spores, as the original supply had died due to mycelial network corruption caused by the ISS Charon. (DIS: "The War Without, The War Within")

In the real world, Prototaxites is an extinct genus of fungi that lived 420 to 370 million years ago. The epithet "stellaviatori" comes from the Latin roots stella ("star"), and viator ("traveler"), hinting at the species' properties.