Which part observed in the cow eye does not appear in the human eye?

Number and variety of living organisms includes genetic, species, and ecological types

Parthenogenesis is a type of reproduction that does not require a mate. it’s rarely seen in birds and higher vertebrates. parthenogenesis involves the formation of a zygote. but this zygote is formed without fertilization. in parthenogenesis, in the absence of a male gamete, the ovum develops directly in the zygote.

What does the number 18.9984 represent in the image?