Its definitly real. The octopus' survival is dependant upon it, so its very specialized and very good at it.

Even tho there is another thread on this, I am going to leave it up here, so long as the discussion centers around how this can apply to cryptids.

Its a good point, if an octopus can do that, and we know that the octopus exists and can't even find it, then imagine what a cryptid can do. Certainly, there must be some types of octopus that remian cryptic because of this ability, and perhaps entire groups of animals are able to do this.

Also notice that in the evolution of the octopus, the eye was developed rather independantly of other animals. Perhaps then this camouflage ability has similarly been independantly developed in other closely related but as yet unknown and speculative animals.