It's rice krispie treats wrapped with fruit rollups and gummi worms and sliced into sections that look like sushi . It's very easy to make too - I have done it a few times. And I know WDW is the first place I ever saw it but I can't remember exactly where.
It is adorable, but its gummy candy (swedish fish, fruit rollups, gummy worms) and rice krispy treats - not two great tastes that taste great together.
(Kids tend to love it - their taste buds tending to enjoy different flavors than that of grown ups, but there are tastier desserts on the grown up menu).