Neopetrolisthes maculatus is a species of porcelain crab (family Porcellanidae) from the Indo-Pacific region. It is a small, colourful crustacean with a porcelain-like shell. This porcelain crab is usually found within the stinging tentacles of a number of sea anemone species
(via: Wikipedia) (photos: T - Steve Childs, B - Nick Hobgood)