This MLSSA muck dive was last year but only recently on reviewing images I noticed some very small sea star like things on the rope and /or cable in this photo (which was taken to show the invertebrates and algae fouling the marker buoy fixation ropes/cables but I didn't see the ? echinoderms on the dive). They look like baby Meridiastra spp. sea stars (which don't occur as adults in this low energy marine artifice as far as I'm aware), BUT could just be artefacts e.g. metal washers with petalled margins (and the creamy white centres would fit with inanimate objects because they might indicate bolts passing centrally through marine-grade washers). Nothing beats rabid guesswork under the rock where I live !!Another thought: could these just be early stage compound ascidian colonies with nearly perfect radial symmetry?
Finally,the sharpest 'sea-star' in image has 11 arms which proves nil but would be consistent with juvenile C. muricata which commonly occurs as adults in West Lakes.