Porcelain crab on bubble tip anemone.

The Internet seems to be full of pictures of this most amazing of creatures, the porcelain anemone crab.
It lives on sea anemones and filter feeds by using its fan-like appendages to gather planktonic organisms that float by.

For some reason, instead of showing this critter in its full glory most pictures tend to show frightened specimens with fans retracted, or even specimens that are out of the water.

The picture above shows the animal sitting on its host anemone and using its fans, in its more natural relaxed state.

Aquarium specimen.