Experiment 243 was the 243rd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to write jokes.
243 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
At the unknown point, he was activated, captured, tamed, and named Pane.
Pane resembles a small weasel of ferret, but walks on two legs rather than four.