Pop-up satellite archival tag
Pop-up satellite archival tags (PSATs) are used to track movements of (usually large, migratory) marine animals. A PSAT (also commonly referred to as a PAT tag) is an archival tag (or data logger) that is equipped with a means to transmit the collected data via the Argos satellite system.
Source: Wikipedia — Pop-up satellite archival tag (CC BY-SA 4.0)