Angstrom Darkwater, QfB
The Fulcrum Star was a power source for an Obsidian Eye. It is a black hole frozen in crystal. The Zoni leader gave one to Angstrom Darkwater so that he could contact them. Later Ratchet found it hidden in Darkwater Cove, then used the Obsidian Eye in Hoolefar Island to locate Clank. Captain Darkwater and Rusty Pete both said it was worth a fortune.
Later when Ratchet and Alister Azimuth used an Obsidian Eye on planet Lumos to contact Clank who was captured in the Great Clock. The Eye's Fulcrum star was cracked so Ratchet and Azimuth lost connection to the Clock a while after opening the connection.