The Guard-Worm is a worm that is shown guarding different locations, such as the Junkyard and a KelpShake restaurant. It's Blackjack's pet.
- The Lost Mattress (major appearance)
- Best Frenemies (cameo)
- BlackJack (cameo)
- Slide Whistle Stooges
- Toy Store of Doom (cameo)
The Guard-Worm is light green with black stripes. It has big yellow teeth protruding from it's lower jaw, and it has a black unibrow. It is usually on a chain collar.
It is quite agressive, and once chased Squidward around Bikini Bottom. However, it can easily be tamed with a game of fetch. She is not the same as Mrs. Wormsley. Somehow, it made it's major appearance in The Lost Mattress.