Which of these characters from "SpongeBob SquarePants" is not a squid?

Gary is not a squid, but rather a snail in the animated series SpongeBob SquarePants. He acts as SpongeBob's loyal and intelligent pet, but his physical characteristics differ from those of a squid. Gary is known for his meowing sound effects and his ability to communicate with SpongeBob through a series of expressive gestures, making him a unique and lovable character within the show.