The origin of the Proty's race is given in Adventure Comics #334. Many centuries earlier a race called the Llorn colonized a planet in the Antares system that was inhabited by race of peaceful creatures. The two races managed to live in harmony until a passing star upset the ecological balance of the planet. The Llorn were forced to evacuate the planet. Before leaving, they used their advanced technology to alter the planet's natives into protoplasmic blobs that could change their shape to suit the environment.
Proty I is rescued from an alien menagerie by the Legion of Super-Heroes, and adopted as a pet by Chameleon Boy. The affectionate alien proves useful to the Legion, and becomes quite close to Saturn Girl, as her telepathic abilities allow her to read its thoughts.
Proty is replaced by Proty II, another member of their race. Proty II later becomes a member of the Legion of Super-Pets.