As river water courses down Mount Hakkai in the Niigata prefecture of Japan, it roils over the dark bluish-green Hakkai stone, or Mushi Gui. Time-produced erosion not only smooths the edges of the rock, but creates irregular holes manifesting a bug-eaten appearance, earning the rock the nickname âBug-Eaten Rock.â This stone is highly prized by aquascaping enthusiasts as they fashion their mystical, glass-encased underwater dioramas, replete with artistically placed layers of stone, wood and aquatic plants. Japanese aquascape legend Takashi Amano introduced the prized Hakkai stone, which was originally developed in the Netherlands in the 1930s, to the hobby. Japanese gardening techniques focus on a more Zen-like minimalism than Dutch inspired creations, and while already popular in Europe and Asia, the art is gaining ground in the United States.