Caldukia
“Caldukia rubiginosa, a proctonotid nudibranch. Porirua, New Zealand.” - via Wikimedia Commons
seen from South Korea
seen from United States

seen from United States
seen from China
seen from United States

seen from United States
seen from Netherlands
seen from Germany

seen from Malaysia
seen from United States

seen from United States
seen from Germany
seen from United States
seen from Germany
seen from United States
seen from Russia

seen from Japan

seen from India
seen from United States
seen from Brazil
Caldukia
“Caldukia rubiginosa, a proctonotid nudibranch. Porirua, New Zealand.” - via Wikimedia Commons
Blue sea dragon!!
Absolutely! I'm surprised we haven't done this one yet!
Have you seen the blue sea dragon (Glaucus atlanticus)?
I have now
Yes, in photos/videos
Yes, irl
I'm not sure
These are also referred to as the sea swallow, blue angel, blue glaucus, dragon slug, blue dragon, blue sea slug, and blue ocean slug.
every time i see a bluebottle or a blue sea dragon posted online all the comments are like "erm... can't that kill you? what the scallop?" my brother in christ venom doesnt always kill you sometimes it's just oof ouch ow. anyway heres a glaucus atlanticus
Flabellina affinis
Robust Frond-aeolis Dendronotus robustus
A nudibranch, or sea slug, from the North American Atlantic coast and the Arctic Ocean. They feed on hydrozoans.
Blue dragon nudibranch (Pteraeolidia ianthina)
Photo by Loh Kok Sheng
Gasflame nudibranch