It is a light olive-green device with a light tan button, a red dial, and a light gray antennae. It is used to track sea sponges within a mile radius.
Role in episode
Sandy invents this tracker after SpongeBob goes to New Kelp City. However, Squidward, not wanting SpongeBob to come back, purposely destroys the device with a hammer, then claims that he he dropped it, but nobody buys his blatant lie for an instant.
This is Sandy’s second invention destroyed in the episode, the first being, her robot.