chiton are really tiny like 5mm at max. they eat algae and live on the tall suger type fronds usually. the spagetti stuff is actually an anilid type worm which feeds by ejecting its rear prtion. I have seen both whilst Diving of the UK
These commensal shrimp were living in my 7" Teardrop Maxima that died recently. I opened the clam and found that it had pulled in a huge piece of LR through the byssal opening, and then healed over it. The rock eventually caused internal damage that killed the clam.
However, during the autopsy I found these two shrimp living INSIDE the clam: