They're sometimes called candy cane beets. I used to work on a farm and we grew all kinds of cool colored and patterned beets.

The German term is "Ringelbete" it's a variant that's supposed to taste a bit more mild and less earthy. Afaik it's mostly used because it looks pretty or if people are not into the usual beet flavor.

This is the beet they were talking about when they were singing "Give me the beet now and free my soul"

It's a Chioggia beet, mostly for cool decoration on a plate.

Im a huge fane of Psychedelic Beets

Sick beet.

Onion-beet!

Beets me!

I've cooked ones like this before, but they never tasted as good as the fully red ones. I guess it's probably due to insufficient water so the beet's not juicy.