Kaolin (clay) is like a large collection of shingles - flat, wide and thin.
When compressed, these plates align as shown in the photo.
This creates a clay "memory" where clay will want to reassume this orientation if bent.
This also creates different shrinkage at each orientation. A stack of pancakes will get shorter as the water between them is removed, or as the butter melts. But the pancakes will tend not to dry less wide.