What is this?

I have had these guys for over a year. They are a blue green i don’t see in euphorbia much, with spines that go from dark red to a black-purple. They are only a few inches tall and it feels like they will stay this mini size.
I don’t think they were getting enough light in my last apartment so i haven’t seen any vertical growth but i think at least on of the arms may be new growth. I got a couple around the same time so i honestly can’t remember.