Cephalopods
Cephalopods are truly the most fascinating creatures to roam the ocean floors. Octopuses in particular are experts at taking note of their environments and then focusing their energies to transform the color and texture of their skin to match! Check out the
incredible video at the bottom of this page. Truly magic! They also mimic other animals. I love this picture -- I think our prototypical conception of an alien was designed after Paraledone octopuses:
I also love cuttlefish -- both to watch and to eat! They look so thoughtful as they swim. They also camouflage themselves, though not quite so precisely as octopuses.
My dream is someday to learn to swim well and scubadive, so I can visit cephalopods in their natural habitat, without getting eaten myself, of course. (This video demonstrates that this is a reasonable fear! WARNING: DO NOT CLICK IF YOU ARE FAINT OF HEART!!)