They're actually a member of the mulberry family.
I saw my first one when I was in college. I don't remember now if it was my ecology class or my dendrology class. But, the fruits fascinate me. They make me think of a green brain. I'll often call it a green brain tree.
One day, I brought home one of the fruits and had it in the house. It started to rot, and I didn't have time to do anything w/it, so I chucked it out the front door. My DD stepped on it, and comes in the house and tells me, Mom, I just stepped on your brain!