What does "pearl hidden in the grass" mean?

There is a mole between the eyebrows, and true wisdom is not easy to show. It's buried deep in the eyebrows, and it's hard to open them until you see the black pearl. This kind of reasonable person has deep thoughts and great thoughts.

Generally speaking, the teacher's eyebrow mole is relatively small, and the color is similar to that of the eyebrows. It is sometimes difficult to find them without careful observation, so this kind of mole has a nice name, which is "hiding pearls in the grass", also called "magpie climbing branches". As the name implies, pearls hidden in the grass are precious pearls hidden in the grass.