A rapid dissection of the eye. One can observe the biconvex lens shaped, the humor, the choroid and the sclerotic. I am not a specialist, but I think that the blackness comes from the pigment cells layer of the internal membrane, meaning the retina. The humor is one of the refringing environments. Then there is the biconvex lens of the eye that can be replaced in surgery for diseases such as cataracts. The choroid is part of the average membrane, and the sclerotic is the fibrous part from the outside, after the cornea that protects the eyeball.