The hologram of Paul Rice was a recreation of the deceased Starfleet officer created on the planet Minos by the Minosian weapon Echo Papa 607.
When Commander Riker, as the USS Enterprise-D first officer, beamed down to Minos, he encountered who he initially believed to be Paul Rice, a former Starfleet Academy classmate. Sensing something was wrong, Riker gave the name of his ship as the USS Lollipop in order to test Rice.
Considering Rice responded to such an obviously absurd answer at face value, Riker soon determined that he was speaking with a holographic version created by the automated weapons unit Echo Papa 607, whose purpose was to extract information from him. Upon realizing that Riker had discovered the ruse, the hologram of Rice disappeared. (TNG: "The Arsenal of Freedom")