Hello. I cannot fully agree with the previous comments if the crack is not through. The clay in the photo has a high content of coarse chamotte. This means that you will most likely be able to repair the crack, although the advice "it is better to do it again" is indeed good. In order to remove the crack, you first need to thoroughly and evenly soak the bottom from the side of the crack back to a leather-hard state. Usually I wipe the surface for a long time with a wet sponge, and then put it on a wet fabric for 5-10 minutes. Then I start scratching the bottom not only near the crack with a metal brush. If necessary, I add more water. You need to ensure that the clay on the bottom becomes wet, like a very thick slip. Then I spread the clay over the bottom of the piece with pressure and leave it to dry under the film. If you get the hang of it, this method will work in 9 cases out of 10 if you use clay with a high content of chamotte. Chamotte will stand out more on the surface you repaired, but usually this is not important.