Question: human eyeballs are ~2.5 cm wide compared to <2cm across; going by this, a Beholder's eye should be bigger than her head.

Even assuming that it just barely fits...where does she keep her brain?

NXTangl said:

Question: human eyeballs are ~2.5 cm wide compared to <2cm across; going by this, a Beholder's eye should be bigger than her head.

Even assuming that it just barely fits...where does she keep her brain?

It's almost completely transparent, and inside her eye.

If she stares at the sun, she dies.

NXTangl said:

Question: human eyeballs are ~2.5 cm wide compared to <2cm across; going by this, a Beholder's eye should be bigger than her head.

Even assuming that it just barely fits...where does she keep her brain?

Anime styled eyes are bigger then real ones so real beholder-chan would have eyes two times smaller.