The first sample of Squilsh was brought back from Mars by the Mars Explorer and was later synthesized by Doc Greene. It is a green gelatinous substance with little-understood properties. A charge of direct current can even bring it to life!
While performing tests on the Squilsh, Doc Greene zapped a blob with electricity, bringing it to apparent life. It ate Greene's scissors before devouring a bucket and escaping from the laboratory. Absorbing matter as it went, the Squilsh headed towards Griffin Rock. The Burns team caught up with it at a park, where Heatwave tried to use water on it, only for it to grow larger. It ate Mister Pettypaws before menacing a group of kids and ingesting Chase. After Heatwave hit it with power lines, the Squilsh ejected Pettypaws. A further attempt to shock the blob failed when it simply swallowed the batteries. The team tracked it to the Griffin Rock Community Pool where it had consumed the contents of the pool, swimmers and all. While it continued to grow, Boulder and Graham Burns used the pool's power supply to explode it, freeing those inside. Doc Greene later gave Cody a Squilsh-powered lava-lamp.
Graham almost knocked over the container by accident while being interviewed by Huxley Prescott. When Prescott was later in need of a way to manufacture a disaster to spice up his reality show, he stole the sample of Squilsh and dumped it in the dam. The Squilsh had soon absorbed all of the water in the area, causing problems when Heatwave and Kade were trying to fight a fire. Following the successful extinguishing of the fire using maple syrup, Doc Greene, Graham and Boulder worked on a way to deal with the Squilsh.