When the viz is bad, I take my macrolens (sometimes with the Nauticam CMC-1 wetlens for a bit of extra magnification) out to the pools. Sometimes I stick to the surface of rocks and seaweeds (to look for stalked jellyfish for instance), but other times I turn over rocks under water to see what hides beneath. Quite a lot! There are larger animals, such as Topknots and different types of crabs (and Worm pipefish as pictured here) but mainly they are quite small (around a centimetre or even less). See the selection below (Tricolia, Bittium and Limacia were not from under rocks but I had to make the grid fit!).
An Bollenessor 
I think a couple of your chitons are Callochiton septemvalvis, see: https://www.inaturalist.org/observations?taxon_id=482196
Thanks Bernard! I have been meaning to upload a bunch of chiton pics on facebook to get ID confirmation – I have some pics of C. septemvalvis which seem very clearcut but these ones confused me a bit. I will update the blog accordingly. cheers Mick
You are right about the unnamed one. I have a set of images where the line between Tonicella marmorea and C. septemvalvis seems to be blurred….Some C. septemvalvis are unmistakable: with the 4 light bands and the longish shape (+tending to be larger and flatter). But some look more like T. marmorea: rounder, with a broader girdle. Then again the distribution does not quite fit and I see that similar-looking things are identified as C. septemvalvis on inaturalist… I am reading up on them a bit before posting on facebook…. Anyway, less hard to find than nudibranchs, also not moving and flat so easier to photograph and the colours are amazing on many of these!