Blue dragon nudibranch (Pteraeolidia ianthina), macro head-on view...

A fantastic (and very large!) Red-margin spanish dancer (Hexabranchus pulchellus)...the Hawaiian swimming crab (Charybdis hawaiensis) in the foreground--apparently ready for his closeup--will give you some scale.

A closer look at the Red-margin spanish dancer (Hexabranchus pulchellus)...