Animals
List incomplete, more probably coming soon.
Glaucus atlanticus
(common names include the blue sea dragon, sea swallow, blue angel, blue glaucus, dragon slug, blue dragon, blue sea slug, and blue ocean slug)
Sea slugs in general are all incredibly beautiful creatures to behold, but this one is my favorite.
Fairy-bluebird
Bloody Belly Comb Jelly
Bargibant's seahorse