A protostar is a star in the very earliest stage of development, when interstellar gas is still undergoing gravitational collapse, and nuclear fusion at the core has just begun. The Argolis Cluster is an example of a protostar cluster.

Collapsing protostars sometimes emit E-band bursts and are often marked by high levels of magnetascopic interference, which impair sensor function.

In theory, a type-6 protostar could be used to generate a wormhole.