She has red eyes and wears a long dark pink dress and light green slippers. Her skin color is similar to Squidward's, only slightly darker and with wrinkles. She has gold earrings and white hair.
In "Chum Fricassee," Grandma Tentacles was shown to be extremely abusive, antagonistic, and hostile towards her grandson Squidward, such as frequently stomping on his foot with her walker and telling the customers to destroy the Chum Bucket in revenge. On the other hand, Squidward had cooked her recipe incorrectly, thus giving the customers severe stomach problems, so her anger was justified. She even stated that she hoped he learn his lesson after ruining her famous recipe, which proved she only wanted him not to try it again.
The female octopus, now known as "Grandma Tentacles", was born to unknown parents.
She married an unknown Grandpa Tentacles.
She gave birth to Jeff Tentacles, the father of Squidward Tentacles.
At some point, she created a recipe for Fricassee.
When Squidward was young, she taught him about her famous recipes.
Grandma Tentacles is mentioned in many episodes. She makes her first physical appearance in "Chum Fricassee."
Despite her rather antagonistic and sadistic side shown in "Chum Fricassee," she was briefly mentioned by Squidward in the episode "The Two Faces of Squidward." He said that she gave him homemade soap thus indicating that she did love and care for him at a certain point.
It is also possible Squidward was refering to his other grandmother.