The Probe was a type of device constructed by the Jaridians.
As their species lacked interdimensional technology, they made the use of sub-light means of dispatching the probes in the search for their ancient foes; the Taelons. They were described as being the celestial version of Earth landmines in the sense that they were launched millions of years ago into deep space. (Episode: The First of its Kind)
After becoming operational, the Probe generated a Replicant that was later responsible for killing the Synod leader Quo'on thus forcing the Taelons to reveal the existence of the Jaridian threat to Joshua Doors. (Episode: The First of its Kind)