Characters in: Wonderland
Although the Gryphon and the Mock Turtle aren't as well known as the characters at the Mad Tea Party, Lewis Carroll spends twice as long describing them. The Mock Turtle is, as the Queen of Hearts explains, the thing that mock turtle soup is made from. Since we don't eat much mock turtle soup these days, you might not get the joke, but it's a soup that tastes like turtle soup but has no turtle in it. In other words, it's the soup that's mock (fake), not the turtle. But Lewis Carroll turns this idea on its head, setting up the fiction that there is an animal called a "mock turtle." Perhaps this is why the Mock Turtle is always crying and sobbing – he wishes he were a real turtle.
The Mock Turtle and the Gryphon spend most of their time with Alice telling her about their school days. The subjects they studied are strange undersea parodies of real school subjects, just as the dance they perform for her, the Lobster Quadrille, is a parody of a popular mid-Victorian dance that the Liddell sisters (the original audience for the Alice books) would have been familiar with. Because they are playful, lighthearted, and focused on their own childhoods, the Mock Turtle and Gryphon seem like the most fitting companions for Alice of all the Wonderland creatures.