No need to confirm again that you didn't understand :D
Ever heard of fables?
"a succinct fictional story, in prose or verse, that features animals, legendary creatures, plants, inanimate objects, or forces of nature that are anthropomorphized, and that illustrates or leads to a particular moral lesson."

The crab is used as an example how many can keep something in order...ah, forget it, it's not worth trying to explain to you.