What is this?

It's growing in my row of kale, but it doesn't look like any of the other kale. I had it under a bottle so at some point it must have looked like the others.
I tried looking it up and the closest I came to a similar kale plant is red russian kale. Interestingly, I didn't buy any packages of red russian kale. So, did a red russian seed get mixed amongst the others or is this a mimic week?

Is it Russian Kale,or an imposter?