Rex is a turquoise worm with yellow eyes and wears a black collar.
Role in the episode
in the episode "Dumped," Rex ironically, left on the bus after SpongeBob was saying worms are "So loyal, so trusting, always by my side!" Rex has only appeared in that episode. Rex was only bought in attempts to make Gary jealous and realize that he should go back to SpongeBob. Rex makes few noises, but he pants and barks maybe once or twice. The only trick he can do is "stay." He did not stay for long considering the fact that almost immediately after that he went to the bus stop.
Rex is a lot similar to Jan and Mr. Doodles, but he has a color shade of light teal.
Similar worms have appeared in other episodes, most recently "Plankton's Pet."
Rex makes an on-screen appearance for about 25 seconds.
Rex resembles an underwater version of a dog as the snails represent underwater versions of cats. For example, SpongeBob expects Rex to do tricks, he barks, and pants with his tongue out.
Rex and Mr. Doodles are very close in color while Jan does not.
Rex almost immediately ditches SpongeBob after about 25 seconds.
Lary, along with Rex, was bought to make Gary jealous.