The meaning of tortoise-backed snake dish

This is just a legend. It is said that in order to celebrate the birthday of the Jade Emperor, all the immortals bring gifts to show their respect, and so do snakes and turtles. When they saw that all the gods and immortals were carrying gifts, but their hands were empty, they were afraid that the Jade Emperor would blame them, so they didn't dare to see them. In the impatience of everyone, the two immortals, the snake and the turtle, came up with a way: put the snake on the turtle's back and make it into a strange shape as a gift to the jade emperor. The jade emperor has everything, and no gift can interest him. When he saw the Snake Fairy and Master Roshi dancing around each other from the outside, he couldn't help laughing.