Data chip
Data Chips were a method of flight recording developed during the Dark Times. They functioned like black boxes, allowing people to trace the ships. This would only be possible with advanced technology, since the chips were older than most other species' history.
The spacecraft Infinite had 4 data chips. Each was small disk with an infinity symbol on it. Each would allow the owner to find the next data chip, until they had all 4 and could find the Infinite. After the Infinite was destroyed, the chips were scattered around the universe. Eventually, Baltazar, Capitan Kaliko, Meregrass and Gurney were all able to obtain a data chip by their time at Volag-Noc. Using the Doctor to track them, Baltazar killed the other three and took their data chips. (DW: The Infinite Quest)