The 2379 discovery on Kolarus III of the scattered parts of B-4, an early Soong android that Shinzon had planted to draw the Enterprise-E towards Romulan space.
B-4 is found in Star Trek Nemesis. On the way to Betazed, the Enterprise-E detects positronic signals from Kolarus III, a world of pre-warp people close to the Neutral Zone. Picard, Data and Worf go down in a shuttle and drive across the desert in the Argo, a wheeled vehicle.
They collect the pieces of an android that looks like Data, and are chased back to the shuttle by armed natives. Reassembled, the android gives his name as B-4. He is a simpler prototype built by Noonien Soong, and Data copies his own memories into him in the hope of helping him to develop.
The find is a trap. Shinzon had obtained B-4 and programmed him to gather information on Starfleet's positions. Data later takes B-4's place to get aboard the Scimitar.