The Precursor core is a location seen in Jak 3. As its name would imply, it is the core of the planet, where the Precursors resided for countless years before leaving Jak's planet on their space shuttle. It was here that the catacombs led, and where the Planetary Defense System was built and maintained.
Jak finally discovered the Precursor core in the latter parts of Jak 3 after a race against Veger in the mission "Reach Precursor core". After the Precursors offer Jak an evolution to a Precursor, Veger steps in with a pistol and steals the "honor". After an outburst from Daxter, the Precursors inside begin to quarrel and accidentally open the door to the oracle control panel they were inside of, revealing themselves to be ottsels using voice modifiers and holographs to depict a mythos, to which Veger replied with disbelief shortly before becoming an ottsel himself.
The core panel itself consists of a large Precursor metal platform with the largest oracle seen in the series at the back. Beneath the oracle is a computer room concealed by two doors. The inside of the control room consists of multiple monitors, one large primary monitor, various buttons, and three floating platforms for each of the Precursors. Surrounding the panel is the core of the planet, consisting of what first appears to be total darkness before being illuminated with networks of dim blue light.