This is Hawaii’s largest nudibranch and can reach a foot long. Mostly active at night, the best chance for snorkelers to see signs of this nudibranch, is to see one of their egg sacs, such as the one in the top photo, attached to a rock. These rose-like sacs are quite beautiful and waver as the water swirls around them.
I’ve only seen an actual Redmargin Spanish Dancer once (second photo). My marine invertebrate book says it resembles fatty ground beef, which is a pretty good description!
Graham's Island 
Fatty ground beef is a good description 😂
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I thought it was pretty good too.
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What a strange looking thing! The egg sack is much prettier.
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I’m with you on that Jo.
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Are you snorkeling or diving when you take all these underwater photos? Ugh – ground beef. Not a pretty creature.
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I’m a snorkeler. Never been diving in m life! This isn’t the prettiest of creatures but the egg sacs are beautiful.
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