sclera
I think it is called a 'Nictating Membrane'.
Yes, when the eyelids are closed, they cover the entire eyeball including the posterior portion. This helps protect the eye from external elements such as dust and debris.
The outer transparent protective cover of the eyeball is the cornea. It helps protect the eye and refracts light to focus it on the retina at the back of the eye.
Exophthalmos
back eye
The Iris.
sclera
Sclera
intraocular fluid
Yes, the outer covering of the eyeball is called the cornea. It is a transparent, dome-shaped layer that helps to focus light into the eye.
schlera choroid
They don't pierce eyeballs.