Rat

A rat was a type of rodent.

At some point prior to Day 5, rats in Hangar BB of Ontario Airport were killed by exposure to the Sentox VX nerve gas that was being stored in the building. When Curtis Manning investigated the airport, he found the dead rats and had Craig bring a forensic team to run tests on them. Trace amounts of the chemical were found in the animals' blood. ("Day 5: 11:00am-12:00pm")

When Jack Bauer found Cheng Zhi on board the Letitcia, he told him that he "should have stayed hidden like a rat". ("Day 9: 10:00pm-11:00am")