Need help. What is this lens?

I have had this huge lens for about 20 years and have never been able to find out anything about it. Could anyone help? I assume it's a old camera or lighting lens. But it's huge. Motion picture lens? Any help would be appreciated.

I got it from my great grandmother after she passed. My great grandfather used to work at Disney and Paramount. So I'm assuming it may have come from either one. Not much info on it. Used to have a hand written note that said "art department"

Thanks for any help

It's over 16 inches wide and over 6 inches deep