Radiolarian

Radiolarian (also called Radiolaria) are microscopic, silica-based organisms that form the biological component of Vex constructs. They control Vex mechanical bodies from a container usually found in the chest, and contact with non-Vex matter can convert a host into a Vex unit. The same substance forms the hazard pool in Radiolarian Fluid. Massive concentrations are found on Vex-transformed worlds such as Nessus.

Acquisition

In the Encore Exotic mission, the Vex Piston sits in a room in the Shadow Legion section, reached after clearing the Shadow Legion and Vex guarding it. Grab the Partition Module that the Partition Minotaur drops and deposit it at a nearby Vex plate to reach the piston. Firing the piston and collecting the samples inside gives Radiolarian used for seasonal gear and challenges.