Well, it's like Yoda. No Yoda is real, but there's "real Yoda" (V, VI) and "CG Yoda" (I, II, III). Same thing for the tentacles. There's CG or drawings, and then there's real material. It's still fictitious, yeah, but it's made of real stuff.
As for octopus sex ... again, I don't know why any...