Along with Mermaid Man and Barnacle Boy, she is one of the three supporting characters who have been retired from the series. Since 2018, Marion Ross has been retired from television, and her character has been limited to non-speaking appearances and off-screen mentions.
She is a dark orange sponge who wears a light green and pink dress and light blue glasses and has light purple hair and pink lips. She enjoys making gingerbread men, chocolate chip cookies, and homemade sweaters with metaphorical love in every stitch. She also is very affectionate and likes to give a lot of kisses, as seen in "Grandma's Kisses."
She is shown to be a very kind and sweet grandmother to SpongeBob. She once treated him like a baby, but later learns that he wanted to be treated like an adult, so she then started treating him as such and let Patrick take SpongeBob's place as a baby, though SpongeBob becomes jealous and wants his grandmother's affection back, but Grandma tells him that he does not have to be a kid for her to love him and that he can enjoy the things he loves and still be an adult.
In the comic Great Grandma, she is shown to have refined cultural tastes. She owns a Stradivarius and owns rare vintage clarinet records; she knows how to make a coral quiche with seaweed butter; she is a talented fine artist and modern dancer. This is something she and Squidward begin to bond over.
When she was an adult, she married the sponge who is now known as Grandpa SquarePants. They had three sons: Harold, Sherm, and Blue.
She now lives alone in her home. Once in a while, she is visited by her family members, usually SpongeBob.
At some point, she met her grandson's best friend, Patrick Star.
She has also been to the Krusty Krab, SpongeBob's job, at least once.
She is so old that she cannot even remember how old she is.
At some point in her life, she gained a driver's license and a car.
At some point, she either invented or obtained a family recipe for Snickerdoodles.
In the video game Employee of the Month, she constantly mistakes SpongeBob for Patrick, even after SpongeBob corrects her.
"No Nose Knows" is the first time where she is mentioned, but doesn't appear.
She is listed as Grandma Sponge in the manual.txt file and the credits for Employee of the Month.