He is a pale yellow sea sponge with olive green holes and white hair. He wears a pine green shirt, a white undershirt, transparent light blue glasses, brown socks, and dark blue slippers. He also holds a black walking cane and a walker. Being an elder, his skin is rather wrinkled and he appears to only have one tooth, which is on the right side of his mouth.
He is first mentioned in "Rock Bottom" and is depicted in SpongeBob's mind in "The Sponge Who Could Fly." He is known for his wise sayings, which include "If we were meant to fly, we'd have propellers on our heads or jet engines on our backs" ("The Sponge Who Could Fly") and "Never run for a bus, especially one that's going up at a 90 degree angle" ("Rock Bottom").
They had Harold, Sherm, Blue, and one other son and one daughter, one other son and two daughters, two other sons and one daughter, or three other sons.
He once said "Never run for a bus, especially one that's going up at a 90 degree angle." and "If we were meant to fly, we had have propellers on our heads or jet engines on our backs."
Late in his life, he had a cane then eventually a walker.
At some point, he may have died, or separated with Grandma Squarepants, as she currently appears to live alone, with there being no mention of him, although it is possible that he just flat out hasn’t been at home during episodes depicting Grandma’s home.