Incidental 21

Incidental 21, also known as Incidental PM13, is a fish who first appears in the episode "Ripped Pants." He is classified as a "hotdog" type incidental.

Description
He is a peach-colored fish with big beady orange eyes and has reddish-brown fins and lips. He wears a teal shirt and has thin black feet.

Incidental PM13
He is a patty monster with a large long head pointing upwards. He also has indigo lips and fins and large yellow eyes.

Role in series
Incidental 21 usually appears as an occasionally used non-speaking incidental that appears in crowds. He was slightly a bit more common in the first three seasons.

"Krabby Patty Creature Feature"
He is turned into a patty monster along with several other Bottomites as Incidental PM13. In the scene where SpongeBob feeds the patty monsters chum at the Chum Bucket, Incidental PM13 shoves the patty monster Old Man Walker out of the way to eat an incoming glob of chum that was originally heading towards the elder.