During the 1970s, a smart unknown California chef, realizing that many Americans did not like the though of eating raw fish, created the now famous California Roll, made with crab, avocado, and cucumbers. Since then, American sushi chefs have created many variations with unique names sugh as Spider Roll, Philadelphia Roll, and Rainbow roll. Most people in Japan have never heard of the California Roll, though, and I would advise not trying to order one there.