Via the Youtube channel of a friend from (but no longer in!) Dublin, Jonathan Gordon, here are some awesome videos of octopus camouflage. (Yes, I know that “octopuses” or “octopodes” is more correct for the plural but “octopi” is more fun!) I’ve seen this kind of thing on documentaries before but never realised this kind of thing could happen when just “[diving] down to look at a shell”.
The screenshots give the game away, sadly, but even when you know it’s there, the camouflage is still so amazing that the octopus is hard to spot.
And if that’s too scary for you, here is another video from Jon featuring an über-cute baby octopus “walking on the beach”: