Experiment 324 was the 324th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to ruin everything.
324 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 Ruinit.
The first 624 experiments, including Ruinit, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.
It is unknown whether Ruinit participated in the following battle between the experiments and the Leroy clones.
The Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song Aloha Oe, which caused the Leroy army to shut down due to the original Leroy's failsafe.
Ruinit is a tall, wiry, large purple prehistoric dog-like experiment with a brown slender body, huge long, droopy, bat-like ears, black eyes, a red-orange round nose, a wide mouth, and a dark pink underbelly.
Ruinit accomplishes his ability to ruin everything, by scheming (such as Snafu), or by making opponents have bad luck (such as Shoe), or by another ability. Like Stitch, he can climb walls, think faster than a supercomputer, see in the dark, and lift objects several times his own weight.