Reaction cube
The reaction cube, also called the spore cube, was a test chamber aboard  starships. On the  it was located in the engineering test bay alpha. ()

On both the Discovery and the , the reaction cube was used to introduce mycelium spores from Prototaxites stellaviatori to a living host as part of the experimental spore drive.

Before the spore drive was perfected, Captain  explained to Michael Burnham the concepts behind the mycelial network by injecting mycelial spores into the reaction cube while she was standing inside of it, showing her different locations across the galaxy. ()

Burnham and Paul Stamets later determined that the Glenns spore drive was experimenting with using a  in the reaction cube to guide the spore drive's navigation. ()

The reaction cube was the only place on a spore drive-equipped ship where the mycelial barrier could be safely contacted. ()

The spore cube could be magnetized, a fact that was used to great effect to neutralize Leland after he was made an agent of Control. ()

In 3189 as part of the Discoverys refit at Federation Headquarters, Adira Tal designed and implemented an upgrade to the control injectors of the reaction cube, replacing them with nanogel control surfaces making it more efficient and comfortable for Stamets.  The Kwejian Courier, Cleveland Booker, was able to use the cube to communicate with the spores. This allowed Discovery to escape from inside the Viridian before its destruction. ()

While escaping from one of Species 10-C's orbs, the spore drive was burned out and, as result, the reaction cube shattered. ()

Spacecraft sections