I find cephalopods endlessly fascinating, but I don’t know the first thing about identifying them! I’d like to broaden my identifying scope to cephalopods too, but I am yet to find a good ID guide on Australian cephalopods. Any suggestions for resources? Free online stuff is preferable, but books are good as well.
Why not take advantage of iNat itself? Take a look at the list of Cephalopod species: can you find morphological cues that distinguishes one species from another? If so, then test your theory out by trying to ID some observations and then tagging some appropriate identifiers to see if you are correct. That is how I kinda learned how to identify Lepidoptera.