The water bear (tardigrade, sw. björndjur) is nature's greatest survivor. It is up to 1,5 mm tall and found everywhere in the world. It can endure the most extreme living conditions.
No Bark, No Bite, but Lots of Fluff: Meet the Poodle Moth
http://photoblog.nbcnews.com/_news/2012/04/18/11271727-see-the-beauties-and-the-beasts-that-live-under-the-sea# ITS A SEA SLUG!!!
Deep sea octopus -SAYABOSOIKA
The Blue Dragon (Glaucus atlanticus), one of the world’s rarest and most beautiful mollusks.
I never thought I'd say this about a bug, but very pretty.
Bathynomus giganteus (Giant Isopod). Giant, deep sea cousin to the Armadillidium vulgare (Common Pill-Bug). Can be over 1ft in length.