Gooble

Swoopin' Stu are transparent creatures that only appear in Super Mario Sunshine. Swoopin' Stu can be found wherever there is toxic Goop. These transparent creatures resemble octopi. Swoopin' Stu come in a variety of colors, and once they spot Mario, they'll turn white for a second before pouncing at him. They make a disturbing "bwooww-wop" noise and can get in Mario's way during battles with Piranha Plants in the Generator. Swoopin' Stus can be destroyed with a blast of water from F.L.U.D.D. or by being jumped on, though the latter method will leave behind a puddle of Goop that can spawn more Swoopin' Stu. Eventually, Swoopin' Stu will pop even without provocation, but will not leave goop.